Chip embedded DC-DC converter

ABSTRACT

A direct current to direct current (DC-DC) converter can include a chip embedded integrated circuit (IC), one or more switches, and an inductor. The IC can be embedded in a PCB. The IC can include driver, switches, and PWM controller. The IC and/or switches can include eGaN. The inductor can be stacked above the IC and/or switches, reducing an overall footprint. One or more capacitors can also be stacked above the IC and/or switches. Vias can couple the inductor and/or capacitors to the IC (e.g., to the switches). The DC-DC converter can offer better transient performance, have lower ripples, or use fewer capacitors. Parasitic effects that prevent efficient, higher switching speeds are reduced. The inductor size and overall footprint can be reduced. Multiple inductor arrangements can improve performance. Various feedback systems can be used, such as a ripple generator in a constant on or off time modulation circuit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 62/293,241, filed Feb. 9, 2016, the entirety of which is hereby incorporated by reference.

BACKGROUND

Field

This disclosure relates to electronic systems, direct current to direct current (DC-DC) converters, electronic device design, and electronic device production technology.

Description of the Related Art

Although various DC-DC converters are known, these DC-DC converters are made of non-ideal components and/or arrangements that suffer from parasitic losses and inefficiencies. There exists a need for improved DC-DC converters.

SUMMARY

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter, comprising: a lower printed circuit board (PCB) part having a bottom side and a top side; an upper printed circuit board (PCB) part having a bottom side and a top side; embedded circuitry that is between the top side of the lower PCB part and the bottom side of the upper PCB part, the embedded circuitry comprising: a pulse width modulator; and at least one switch; one or more vias extending through the upper PCB part; an inductor positioned over the top side of the upper PCB part, wherein the one or more vias are electrically coupled to the inductor and to the embedded circuitry. The embodiments can feature any combination of: wherein the embedded circuitry includes an integrated circuit (IC); wherein a footprint of the inductor at least partially overlaps a footprint of the integrated circuit; wherein no wire-bonds electrically interconnect the inductor and the embedded circuitry; wherein the circuitry has a switching rate of at least 1 MHz; wherein the circuitry has a switching rate of at least 3 MHz; wherein the circuitry has a switching rate of at least 5 MHz; wherein the circuitry has a switching rate of up to 7 MHz; wherein the at least one switch comprises an enhanced gallium nitride field effect transistor (eGaN FET); further comprising one or more capacitors disposed over the top side of the upper PCB part; further comprising a core disposed between the top side of the lower PCB part and the bottom side of the upper PCB part, wherein the core has one or more pockets formed therein, and wherein the embedded circuitry is disposed in the one or more pockets; wherein the DC-DC power converter has a footprint that is smaller than 25 mm²; wherein the DC-DC power converter has a footprint that is smaller than 10 mm²; wherein the DC-DC power converter has a footprint that is smaller than 5 mm²; wherein the DC-DC power converter has a footprint that is as small as 2 mm²; wherein the DC-DC power converter has a footprint area that is between 0.5 and 10 mm² per amperage of current.

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter package comprising: an integrated circuit (IC) chip embedded in at least one printed circuit board (PCB), the IC chip comprising a driver; an inductor positioned outside of the chip embedded package and coupled to a surface of the chip embedded package; and a via electrically coupling the inductor to the IC chip; wherein a footprint of the inductor overlaps, at least partially, with a footprint of the IC chip. The embodiments can feature any of: wherein a transistor is embedded in the at least one PCB, and wherein the inductor is electrically coupled to the transistor; wherein the IC chip comprises: a pulse width modulator (PWM) controller coupled to the driver, and a switching transistor coupled to an output of the driver; further comprising a switch comprising enhanced gallium nitride (eGaN); wherein the switch is configured to switch at 4 MHz or faster; wherein the switch is configured to switch at 5 MHz or faster; further comprising a switch comprising at least one of silicon or gallium arsenide.

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter in a single package comprising: an enhanced gallium nitride (eGaN) component embedded, at least partially, inside of a mounting substrate; an inductor mounted outside of the mounting substrate; and a via coupling the inductor to the eGaN component; wherein a footprint of the inductor overlaps, at least partially, with a footprint of the eGaN component. The embodiments can feature any combination of: wherein the mounting substrate is a multi-layer PCB; wherein the eGaN component is a switch comprising eGaN, the DC-DC power converter further comprising a driver circuit configured to drive the switch; wherein the driver and the switch are part of an IC chip; wherein the IC chip further comprises a pulse width modulator (PWM) controller.

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter utilizing a chip embedded package, the DC-DC converter comprising: an enhanced gallium nitride (eGaN) switch inside of a printed circuit board (PCB); a pulse width modulator (PWM) controller; a driver embedded inside of the PCB, wherein the PWM controller and the driver are configured to drive the eGaN switch at a frequency of 1 MHz or higher; an inductor positioned outside of the chip embedded package and coupled to a surface of the PCB; and a via electrically coupling the inductor to the eGaN switch. The embodiments can feature wherein the driver is configured to drive the eGaN switch at a frequency of 5 MHz or higher.

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter comprising: a printed circuit board; and an integrated circuit inside of the printed circuit board, the integrated circuit comprising a driver. The embodiments can feature any combination of: further comprising an inductor electrically coupled to the integrated circuit by one or more vias that extend through the printed circuit board; wherein the inductor has a footprint that at least partially overlaps a footprint of the integrated circuit.

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter comprising: an integrated circuit comprising a driver; and an inductor vertically stacked above the integrated circuit such that a footprint of the inductor overlaps, at least partially, with a footprint of the integrated circuit, wherein the inductor is electrically coupled to the integrated circuit. The embodiments can feature any combination of: further comprising a printed circuit board (PCB) having a first side and a second side that is opposite the first side, wherein the integrated circuit is mounted on the first side of the PCB, and wherein the inductor is mounted on the second side of the PCB; wherein the inductor is electrically coupled to the integrated circuit by one or more vias that extend through the printed circuit board.

Some embodiments are disclosed for a direct current to direct current (DC-DC) buck converter comprising: one or more switches; a driver configured to drive the one or more switches; and an inductor electrically coupled to the switches; wherein the footprint of the DC-DC buck converter is less than 65 mm²; wherein the DC-DC buck converter is configured to receive at least 20 amps of current; and wherein the DC-DC buck converter is configured to output at least 20 amps of current.

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter comprising: one or more switches; a driver configured to drive the one or more switches at a frequency, the frequency being between 1 and 5 MHz inclusive; and an inductor electrically coupled to the one or more switches; wherein the footprint of the DC-DC converter is less than or equal to 10 mm²; wherein the DC-DC converter is configured to receive at least 5 amps of current; wherein the DC-DC converter is configured to output at least 5 amps of current.

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter comprising: a first switch coupled to a first inductor; a second switch coupled to a second inductor; and an integrated circuit chip embedded in a printed circuit board; wherein the first switch and the second switch are coupled to a modulator; and wherein the first inductor and the second inductor are coupled to a voltage output node. The embodiments can feature any combination of: wherein the modulator is included in the integrated circuit chip; wherein the modulator is configured to cause the first switch and the second switch to operate output of phase with a synchronous period; wherein an output signal at the output node is a superposition of a first signal through the first inductor and a second signal through the second inductor.

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter comprising: an integrated circuit chip embedded in a printed circuit board, the integrated circuit chip comprising a driver; a first switch coupled to the driver; an inductor coupled to the first switch; and a feedback path from an output node to a modulator circuit. The embodiments can feature any combination of: wherein the modulator circuit is a voltage mode modulator circuit: wherein the modulator circuit is a constant on time or constant off time modulator circuit: wherein the modulator circuit is included in the integrated circuit chip: wherein the modulator circuit and the inductor are included in a package with the integrated circuit chip.

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter comprising: an integrated circuit chip embedded in a printed circuit board, the integrated circuit chip comprising a driver; a first switch coupled to the driver; an inductor coupled to the first switch; a feedback path from an output node to a modulator circuit; and a ramp generator. The embodiments can feature any combination of: wherein the feedback path and an output from the ramp generator are coupled to a comparator; further comprising a reference voltage source coupled to the comparator; wherein the ramp generator is configured to emulate a ripple current through the inductor; wherein the ramp generator comprises; a first current source, a second current source, and a capacitor; wherein the first current source and the second current source are configured to be trimmed based, at least in part, on an inductance of the inductor; wherein the ramp generator and the inductor are included in the same DC-DC power converter package; wherein the ramp generator is configured to generate an output signal that is unaffected by an output capacitor coupled to the inductor; wherein the ramp generator is configured to generate an output signal that is independent from the equivalent series resistance (ESR) of an output capacitor coupled to the inductor; further comprising an output capacitor having a sufficiently low ESR such that a ripple voltage across the output capacitor is too small to reliably provide to a modulation circuit.

Some embodiments are disclosed for a ramp generator comprising: a first current source coupled to a supply voltage; a second current source coupled to ground; and a capacitor coupled between the first current source and the second current source. The embodiments can feature any combination of: wherein the ramp generator is configured to emulate a ripple current through an inductor in a DC-DC converter; wherein the output of the first current source is based, at least in part, on an input voltage to a DC-DC converter; wherein the output of the first current source is based, at least in part, on an inductance of an inductor in a DC-DC converter; wherein the output of the second current source is based, at least in part, on an inductance of an inductor in a DC-DC converter; wherein the output of the second current source is based, at least in part, on an inductance of an inductor in a DC-DC converter; wherein the first current source is configured to be trimmed based, at least in part, on an inductance of an inductor in a DC-DC converter; wherein the second current source is configured to be trimmed based, at least in part, on an inductance of an inductor in a DC-DC converter.

Some embodiments are disclosed for a method for making a chip embedded direct current to direct current converter comprising: embedding an integrated circuit chip in a printed circuit board; coupling a first inductor to the printed circuit board; and coupling a second inductor to the printed circuit board, the first inductor and the second inductor both coupled to an output node.

Some embodiments are disclosed for a method for converting first direct current voltage to a second direct current voltage comprising: driving a first switch coupled to a first inductor; driving a second switch coupled to a second inductor, wherein the first switch and the second switch are coupled to an output node; and modulating the driving of the first switch and the second switch out of phase; wherein at least one of a driver or a modulator is included in a chip embedded in a printed circuit board.

Some embodiments are disclosed for a method for making a chip embedded direct current to direct current converter comprising: embedding an integrated circuit chip in a printed circuit board; coupling an inductor between the integrated circuit chip and an output node; and providing a feedback path from the output node to a modulator circuit, wherein the modulator circuit includes a ramp generator. The embodiments can feature any combination of: wherein the modulator circuit is included in the printed circuit board; wherein the modulator circuit is a constant on time or constant off time modulator circuit; wherein the ramp generator is included in the integrated circuit; further comprising trimming the ramp generator based at least in part on the property of the inductor; wherein the ramp generator is the ramp generator of any previous embodiment.

Some embodiments are disclosed for a method for using a direct current to direct current converter comprising: receiving input power at an input node; providing power through a switch to an inductor; storing energy in an output capacitor such that an output voltage forms across the output capacitor; providing output power at the output voltage to an output node; providing the output voltage to a modulator circuit; generating a ripple voltage that is independent of an output capacitor; providing the ripple voltage to the modulator circuit; modulating the switch based at least in part on an output of the modulator circuit. The embodiments can feature any combination of: further comprising comparing at least two of: the ripple voltage, a reference voltage, and the output voltage; further comprising trimming a current source based at least in part on an inductance of the inductor; wherein the ripple voltage is generated by a ramp generator configured to emulate a current through the inductor.

Some embodiments are disclosed for a direct current to direct current (DC-DC) power converter package comprising: an integrated circuit (IC) chip embedded in at least one printed circuit board (PCB), the IC chip comprising a driver; an inductor positioned outside of the chip embedded package and coupled to a surface of the chip embedded package; and an overcurrent protection circuit configured to detect when a current provided to the inductor exceeds a limit. The embodiments can feature any combination of: the overcurrent protection circuit comprises a current source configured to be adjusted or trimmed based at least in part on an Inter-Integrated Circuit or Power Management Bus command; a saturation inductance of the inductor exceeds the limit and exceeds the limit by less than 50%; the limit exceeds a maximum specified DC current specification plus maximum alternating current ripple specification by less than 50%.

Some embodiments disclosed herein can relate to a direct current to direct current (DC-DC) power converter package comprising: an integrated circuit (IC) chip embedded in at least one printed circuit board (PCB), the IC chip comprising a driver; an inductor positioned outside of the chip embedded package and coupled to a surface of the chip embedded package; and an Inter-Integrated Circuit or Power Management Bus. The embodiments can have any combination of: wherein the Inter-Integrated Circuit or Power Management Bus is coupled to at least one current source and configured to provide a protocol command to adjust or trim the current source; wherein the Inter-Integrated Circuit or Power Management Bus is coupled to at least one current source and configured to provide a protocol command to set or adjust a reference value provided to a comparator; wherein the Inter-Integrated Circuit or Power Management Bus is configured to communicate protocols comprising instructions to perform at least one of: turn on or off the DC-DC power converter package, change a low power or sleep mode of the DC-DC power converter package, read out information about current settings of the DC-DC power converter package, read out diagnostic and/or technical information about the DC-DC power converter package, set or change an output voltage provided by the DC-DC power converter package; wherein a Power Management Protocol is implemented as an interconnect layer on top of an Inter-Integrated Circuit implementation

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example circuit level schematic of a chip embedded DC-DC converter package.

FIG. 2 shows a package level schematic of an example embodiment of a chip embedded DC-DC converter package.

FIG. 3 shows a cross section view of an example chip embedded DC-DC converter.

FIG. 4A shows a perspective view of an example chip embedded DC-DC converter with a stacked inductor.

FIG. 4B shows a reverse perspective view of an example rendered chip embedded DC-DC converter with a stacked inductor.

FIG. 4C shows a side view of an example chip embedded DC-DC converter with an embedded stacked inductor.

FIG. 4D shows a side view of an example chip embedded DC-DC converter with an embedded inductor.

FIG. 5 shows a see-through perspective view 500 of an example chip embedded DC-DC converter.

FIG. 6 shows a bottom view of an example chip embedded DC-DC converter.

FIG. 7A shows an example of a DC-DC converter used in a memory device.

FIG. 7B shows an example of a chip embedded DC-DC converter used in a memory device.

FIG. 8A shows an example application of DC-DC converters on a circuit board.

FIG. 8B shows an example application of chip embedded DC-DC converters on a circuit board.

FIG. 9 shows a flowchart of an example method for making and using a chip embedded DC-DC converter.

FIG. 10 shows an example dual inductor design for a dual buck converter using a chip embedded DC-DC converter.

FIG. 11A shows a first example layout design for the embedded chip in a dual buck converter.

FIG. 11B shows a second example layout design for embedded chips in a dual buck converter.

FIG. 11C shows a third example layout design for embedded chips in a dual buck converter.

FIG. 11D shows a fourth example layout design for embedded chips in a dual buck converter.

FIG. 12 shows an example circuit level schematic of a dual buck converter including a chip embedded DC-DC converter.

FIG. 13A shows an example circuit level schematic of a DC-DC converter including a chip embedded DC-DC converter.

FIG. 13B shows an example circuit level schematic of a DC-DC converter including a chip embedded DC-DC converter.

FIG. 14 shows an example chip embedded DC-DC converter with an external ripple voltage feedback circuit.

FIG. 15 shows example graphs of inductor current I_(L) over time and equivalent series resistance voltage V_(ESR) (also referred to as ripple voltage) over time.

FIG. 16 shows an example chip embedded DC-DC converter with an external ripple voltage feedback circuit.

FIG. 17 shows an example chip embedded DC-DC converter with an internal ripple voltage feedback circuit.

FIG. 18 shows an example circuit level schematic of a ramp generator.

FIG. 19 shows an method for shows an example method of making and using a DC-DC converter.

DETAILED DESCRIPTION

Introduction

Direct current (DC) to direct current (DC-DC) converters are a type of electronic circuit. DC-DC converters can receive input power at a first voltage and can provide output power at a second voltage. Examples of DC-DC converters include boost converters (which can have a higher output voltage than the input voltage), buck converters (which can have a lower output voltage than the input voltage), buck-boost converters, and various other topologies.

Some DC-DC converters are affected by non-ideal component characteristics. These can include parasitic inductances, parasitic capacitances, and/or parasitic resistances caused by components such as wire bonds and leadframe packages such as quad flat no-lead (QFN) packages, power quad flat no-lead (PQFN) packages, dual flat no-lead (DFN) packages, micro lead-frame (MLF) packages, etc. Furthermore, interconnections between internal components of the DC-DC converter, such as from a driver to switches, can also contribute to parasitic effects. These parasitic effects can limit the switching speed and/or efficiency of DC-DC converters.

This disclosure includes examples of highly integrated solutions where the DC-DC converter can switch more efficiently, switch at higher frequencies, and/or offer improved performance with a reduced package footprint. An integrated circuit chip that integrates many DC-DC components such as a pulse-width modulator controller, a driver, and/or one or more enhanced gallium arsenide switches (also known as enhancement mode gallium arsenide switches and eGaN FETs) can be included in a package. The integrated circuit can be embedded in a printed circuit board, or embedded between printed circuit boards. The package can include an inductor and/or capacitor in a vertical design to reduce the package footprint. Certain features can reduce the parasitic effects that would otherwise prevent achieving higher switching speeds and/or higher efficiency. By efficiently achieving higher switching speeds, the inductor size can then be reduced. The DC-DC converter can operate at higher frequencies, offer better transient performance, have lower ripples, use fewer capacitors, and/or reduce the overall footprint.

For purposes of providing an introduction, certain aspects, advantages, and novel features have been introduced. It is to be understood that not necessarily all such aspects, advantages, and novel features of the introduction are achieved in accordance with any particular embodiment. Thus, one or more aspects, advantages, and novel features may be achieved without necessarily achieving the other aspects, advantages, and novel features disclosed herein. It is also to be understood that not all aspects, advantages, and novel features have been disclosed in the introduction.

Example Schematic Diagram

FIG. 1 shows an example circuit level schematic of a chip embedded DC-DC converter package 100. The schematic shows a power input port 101, a power source 103, an input capacitor 105, a ground port 106, ground 107, a voltage output port 109, an output capacitor 111, an integrated circuit (IC) chip 113A, an alternative IC 113B, a driver 117, a pulse width modulator (PWM) controller 119, a first electric pathway 121, a first switch (e.g., a first enhanced gallium nitride (eGaN) switch) 123, a second electric pathway 125, a second switch (e.g., a second eGaN switch) 127, a third electric pathway 129, an inductor 131, and an AC bypass capacitor 133. A dotted line 135 indicates an alternative, separate packaging of the switches 123, 127. The switches 123, 127 can also be referred to as power switches, switching FETs, and/or switching transistors. The schematic also shows a current source 137, a comparator 139, and fault logic and/or over current protection circuitry 141.

The chip embedded DC-DC converter package 100 can be coupled through the power input port 101 to the power source 103 and also coupled through the input capacitor 105 to ground 107. The chip embedded DC-DC converter package 100 can also include a voltage output port 109 that can be coupled through the output capacitor 111 to ground 107. The chip embedded DC-DC converter package 100 can also include the ground reference port 106 that is coupled to ground 107.

The chip embedded DC-DC converter package 100 can have a printed circuit board (PCB) that includes an embedded integrated circuit (IC) chip 113A or 113B. The IC can include a driver 117 and/or a pulse width modulator (PWM) controller 119. By way of example, the first electric pathway 121 couples the IC to the gate of a first eGaN switch 123. The second electric pathway 125 couples the IC to the gate of the second eGaN switch 127. The third electric pathway 129 couples the IC to a source of the first eGaN switch 123, a drain of the second eGaN switch 127, and to the inductor 131. The inductor 131 can be coupled to the voltage output port 109. An AC bypass capacitor 133 can be coupled from the drain of the first eGaN switch 123 to the source of the second eGaN switch 127 to short AC signals to ground 107.

Although FIG. 1 shows the driver 117 and the PWM controller 119 as part of the IC 113A, in various embodiments, the IC can include one of the PWM controller 119 or the driver 117 while the other of the PWM controller 119 and the driver 117 is separately coupled to the IC 113A. In some embodiments, one of the eGaN switches 123, 127 or the pair of eGaN switches 123, 127 can be integrated into the IC 113A along with the respective electric pathways 121, 125, and/or 129. The IC 113A can be a semiconductor. The IC 113A can be a silicon, gallium arsenide, gallium nitride, eGaN, or other III-V material based semiconductor. Accordingly, any integrated components, can also be made of a material the same as or similar to the IC 113A. The switches 123, 127, electric pathways 121, 129, 125, driver, 117, and PWM controller 119 can also be made of the same or similar material as the IC 113A.

The pair of switches 123, 127 can be monolithic eGaN field effect transistors (FETs). In some embodiments, the pair of switches 123, 127 can be separate devices, including two standalone eGaN FETs. In some embodiments, the switches 123, 127 are metal oxide field effect transistors (MOSFETs). Various other numbers or types of switches can be used in various other embodiments. Although many embodiments describe the switches 123, 127 as eGaN switches, other suitable materials can be used instead of or in addition to eGaN.

In some embodiments, the electric pathways 121, 129, 125 can be implemented with vias such as copper pillars, traces, and/or other electric pathways with low parasitic effects (e.g., low parasitic inductance, low parasitic resistance, and/or low parasitic capacitance). Wire bonds can have higher parasitic effects (e.g., higher parasitic inductance, higher parasitic resistance, and/or higher parasitic capacitance).

The ports, including power input port 101, ground port 106, and voltage output port 109, can be implemented as pads, pins, or other electric conductor with low parasitic effects (e.g., low parasitic inductance, low parasitic resistance, and/or low parasitic capacitance). The ports can be designed to couple to traces on another device such as a motherboard, PCB, etc.

Many variations are possible. In some embodiments, bypass capacitor 133 can be omitted. Some embodiments can feature different inductors, capacitors, magnets, and/or resonant arrangements. The various components shown in the example schematic of FIG. 1 form a DC-DC converter, but DC-DC converters can have other variations. It will be appreciated that the teachings disclosed herein can extend to DC-DC converters of other variations.

By way of example, the DC-DC converter 110 can receive a power signal through the power input port 101 from the power source 103. The power signal can be filtered through shunt input capacitor 105 that can act as a decoupling capacitor to filter noisy alternating current (AC) signal components. The power signal is provided to the drain of the first switch 123 of a pair of switches 123, 127.

A driver 117 provides a first control signal through the electric pathway 121 to the gate of the first switch (e.g., eGaN switch) 123. The driver also provides a second control signal through the electric pathway 125 to the gate of the second switch (e.g., eGaN switch) 127. Using the control signals, the driver can turn the switches 123, 127 on and off in alteration. The driver can control the signal such that the on/off state of the first switch 123 is opposite of the on/off state of the second switch 127. The on/off duty cycles of the control signals can be set by the PWM controller 119. The PWM controller 119 can also control the pulse width or period through PWM signals provided to the driver.

The switches 123, 127, IC 113A (e.g., including the PWM controller 119 and/or driver 117), and the inductor 131 can be arranged to form part of a non-isolated synchronous power converter or a power stage. When the driver 117 drives the first switch 123 on and drives the second switch 127 off, power can be provided from the power source 103 to an energy storage circuit, such as the inductor 131 and/or capacitor 111, causing the DC output voltage at voltage output port 109 to increase. While driver 117 drives the first switch 123 off and drives the second switch 127 on, power from the energy storage circuit can drain through the second switch 127 to ground 107, causing the DC output voltage at voltage output port 109 to decrease. Accordingly, the pair 123 of switches 123, 127 can be quickly toggled to control the DC output voltage at voltage output port 109. The inductor 131 and capacitor 111 also act as a resonant filter that helps regulate the DC voltage.

The comparator 139 has a first input coupled to the drain of the second switch 127. The comparator 139 has a second input coupled to the source of the second switch 127. Accordingly, the comparator 139 can be coupled across the second switch 127. In some embodiments, the comparator 139 can have an inverting terminal as the first input. The first input of the comparator 139 can also be coupled to a current source 137. An I²C and/or PMBUS (further described with respect to FIG. 2) can be used to trim and/or adjust the output current of current source 137. Accordingly, an overcurrent limit can be set and/or adjusted. The output of the comparator 139 can be provided to fault logic and overcurrent protection (OCP) circuitry 141.

The comparator 139 along with the fault logic and OCP circuitry 141 are configured to sense the drain-source resistance R_(ds) when the switch 127 is on. The voltage drop across the switch 127 caused by R_(ds) is compared to a reference value that can be adjusted by trimming or adjusting current source 137. The output of the comparator 139 can trip when an overcurrent condition occurs. The overcurrent protection circuitry 141 can turn off the switches 123, 127 and/or the driver when an overcurrent condition is detected and enter fault mode. In various embodiments, the OCP circuitry can couple directly to the gates of the switches 123, 127 to turn off the switches, short one or more alternative energy pathways (not shown) to discharge energy, affect the PWM controller 119 outputs in response to an overcurrent condition, and/or affect the driver 117 outputs in response to an overcurrent condition. In fault mode, the system can make periodic attempts to recover by briefly turn on the switches 123, 127 and/or driver, attempt to detect the overcurrent condition, and if the overcurrent condition still persists, turn off the switches 123, 127 and/or driver 117, and wait for a period of time before re-attempting to recover.

Sometimes, overcurrent conditions can occur as a result of inductor saturation. An inductor, such as inductor 131, can saturate if too much current is provided to the inductor for too long and lose its magnetic properties. In such cases, the inductance of an inductor can drop by 10%, 30%, or even more. A fully saturated inductor can effectively act as a wire, creating a potential short in the circuit. During saturation, the effective resistance of the inductor can drop, causing the output current to increase beyond specification and to potentially unsafe levels. The LC resonance of the circuit can also be affected when the inductor no longer effectively stores energy, so overvoltage and/or under voltage conditions can occur.

The inductor 131 can be selected to tolerate the load current (DC output current) as well as an AC ripple. Accordingly, the saturation current limit of the inductor 131 can be selected to exceed a specified DC output current plus the maximum AC ripple. For example, if the chip embedded DC-DC converter generates a 10 A DC current and a +/−5 A ripple, then the maximum total current is 15 A, and the inductor saturation limit should exceed 15 A. Inductors with higher inductances can have higher saturation limits and be larger in size.

In some designs, determining the overcurrent protection limits and determining the inductor size can be determined independently from each other, and one or the other can be over-engineered. This can occur, for example, when a second party selects and couples inductors to a DC-DC converter otherwise made by a manufacturer. In some cases, the second party may over-engineer the inductor out of an abundance of caution, for example, by allowing for a 5 A AC current, a 10 A DC current, and a 100% DC overcurrent, such the inductor is selected to have a saturation limit of 25 A or more. In some cases, the second party may not know OCP limits, and therefore resort to over-engineering the inductor to be larger in inductance and size such that the inductor is not saturated. In some cases, a second user could otherwise use a smaller inductor but for overcurrent protection limits that are too high, and therefore use an inductor of a minimum size and inductance that are larger than otherwise necessary. In some cases, a manufacturer may set an overcurrent limit too high or too low. Some embodiments of DC-DC converters disclosed herein can include an adjustable overcurrent limit. Some embodiments of DC-DC converters disclosed herein can include both overcurrent protection circuitry and an inductor, wherein the overcurrent limit is determined based at least on the size of the inductor, and the overcurrent limit can be set to a value equal to and/or below the saturation limit of the inductor. Some embodiments of DC-DC converters disclosed herein can include both overcurrent protection circuitry and an inductor, wherein the size of the inductor is selected, based at least in part, on the overcurrent limit, such that the saturation limit of the inductor is equal to or exceeds the overcurrent limit by a narrower margin such as 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or any values therebetween, or ranges bounded by any of these values, etc. Some embodiments of DC-DC converters disclosed herein can have overcurrent limits set to be less than the expected maximum AC current plus twice the expected DC current, such as a 90% or less DC overcurrent, a 75% or less DC overcurrent, a 50% or less DC overcurrent, 50% or less DC overcurrent, 40% or less DC overcurrent, 30% or less DC overcurrent, 20% or less DC overcurrent, 10% or less DC overcurrent, or any values therebetween, or ranges bounded by an of these values, etc. In some embodiments, a single designer can provide the components for and select the values for both the OCP circuit and limits as well as the inductor and its saturation limit. Accordingly, in some embodiments, the DC-DC converter can operate without the inductor reaching saturation while having a smaller footprint, lower inductor direct current resistance, and increased efficiency.

Packaging

FIG. 2 shows a package level schematic of an embodiment of a chip embedded DC-DC converter package 100. The chip embedded DC-DC converter package can include input port 101, ground port 106, and output port 109. As described with respect to FIG. 1, a power input port 101 can be coupled to a power source 103, such as by way of an input capacitor 105 that is coupled to ground. A voltage output port 109 can supply a DC output voltage to a load coupled at node 201, such as by way of an output capacitor 111 that is coupled to ground 107. An enable port 205 is configured to receive a signal to enable the DC-DC converter. A test port 203 can be used to check the status of the device. In some embodiments, an Inter-Integrated Circuit (I²C) and/or Power Management Bus (PMBUS) provides a communication pathway to/from the chip embedded DC-DC converter package 100.

The package 100 footprint can include all the components of a DC-DC converter. In some embodiments, the package 100 footprint includes the IC 113A or 113B and an inductor 131, for example such that the package can operate as a DC-DC converter without additional external inductors. In some embodiments, at least one or more of capacitors 105, 111, and/or 133 can also be included within the package footprint, for example such the package can operate as a DC-DC converter without additional external capacitors.

In some embodiments, the I²C and/or PMBUS can be used to receive I²C and/or PMBUS protocol communications to perform one or more of the following: turn on or off the chip embedded DC-DC converter package 100, change a low power or sleep mode of the DC-DC converter package 100, read out information about current settings of the DC-DC converter package 100, read out diagnostic and/or technical information about the DC-DC converter package 100, set or change an output voltage provided by the DC-DC converter package 100 (e.g., by changing a digital signal provided to the digital to analog controller “DAC” described with respect to FIG. 16 and FIG. 17), trimming a property of the ramp generator (e.g., the ramp generator of FIG. 17) such as amplitude or frequency, trimming one or more current sources (e.g., the current sources of FIG. 18), and other functions. In some embodiments, the PMBUS protocol is implemented as an interconnect layer on top of the I²C implementation.

Integration and Chip Embedded Design

The DC-DC converter can be highly integrated and can switch at higher frequencies and offer improved performance as compared to other DC-DC converters. In some designs, parasitic effects prevent can prevent DC-DC converters from efficiently operating at higher frequencies (higher switching speeds), if at all. A number of designs for DC-DC converters are disclosed herein along with additional designs with reduced parasitic effects.

Some DC-DC converter packages include wire bonds and/or leadframe packages. An example 1 mil, 1 mm long bond wire may have 0.7 nH of parasitic inductance, 0.08 pF of parasitic capacitance, and 140 mΩ of parasitic resistance. Similar or higher parasitic effects can result from leadframe packages such as quad flat no-lead (QFN) packages, power quad flat no-lead (PQFN) packages, dual flat no-lead (DFN) packages, micro lead-frame (MLF) packages, etc. Some embodiments of DC-DC converters disclosed herein can limit or avoid the use of wire bonds and/or leadframes altogether in order to reduce parasitic effects. Vias, traces, bumps, and/or bump pads can be used inside of a package instead.

Some DC-DC converter packages do not include an inductor or capacitor. Such packages give a user the flexibility to select particular values for the capacitors and inductors and control the quality of those components. The DC-DC converter package, inductors, and capacitors may be surface mounted on a motherboard or separate PCB and coupled together with wire bonds or long traces through the motherboard or the separate PCB (for example, as shown in FIG. 7A). However, coupling a DC-DC converter package to the external inductors or capacitors can introduce parasitic effects. Parasitic effects can similarly be introduced between the inductor and a load. Some embodiments of DC-DC converters disclosed herein can reduce parasitic effects of coupling to the inductor or capacitor by integrating the inductor or capacitor in the same package as the other components of the DC-DC converter. In some embodiments disclosed herein, the electric pathways coupling to the inductors or capacitors can be implemented with vias and/or traces instead of wire bonds. In some embodiments disclosed herein, the electric pathways coupling to the one or more inductors or capacitors can include vias and/or traces located in the PCB of the DC-DC converter instead of including traces in the motherboard or separate PCB (e.g., as shown in FIG. 3 and FIG. 7B). In some embodiments disclosed herein, any combination of the PWM controller, driver, inductor(s), capacitor(s), and/or switch(es) can be included in the same package.

In some designs, parasitic effects can arise as a result of component interconnections. For example, with respect to FIG. 1, a driver 117 in one integrated circuit 113A can couple to a separate electronic component 135 that includes switches 123, 127. The integrated circuit 113A and the separate electronic component 135 can be included in a PCB. The electric pathways 121, 129, 125 between the driver and the switches 123, 127 can be implemented using traces on the PCB, but the traces on a PCB can have relatively higher parasitic effects as compared to electric pathways inside integrated circuits. Some embodiments of DC-DC converters disclosed herein can reduce parasitic effects of interconnections between the driver and switches by integrating the switches 123, 127, and driver 117 along with their interconnections in the same IC 113B. In some embodiments disclosed herein, the PWM controller, driver, and switches are all included in the same IC 113B. In some embodiments, one or more capacitors can also be include in the same IC 113B.

In some designs, MOSFET switches can be used. However, MOSFET switches can be less efficient at higher switching speeds. In some embodiments disclosed herein, the switches 123, 127 can be eGaN switches. eGaN switches can switch more efficiently and at higher speeds compared to MOSFET switches.

The synergy of the techniques disclosed herein will be appreciated. Parasitic capacitance and/or inductance effects can limit maximum switching speeds in a DC-DC converter. This may be because the parasitic effects can cause undesired energy to be stored, affecting the charging and discharging of energy, and thereby affecting DC voltage regulation. The parasitic effects can also cause the switches to turn on or off slowly. In some embodiments, a combination of the techniques disclosed herein can cause the parasitic effects to be reduced by a sufficient degree for improvement in DC-DC converter performance. Additional synergies relating to the arrangement, size, and performance of DC-DC converters are also discussed in later sections of the detailed disclosure.

Compared to some other DC-DC converters, some embodiments disclosed herein remove about 40 bond wires, which can reduce parasitic effects by about 20 mΩ and can also reduce the package leakage inductance (parasitic inductance) by 10 nH or more. The elimination of these parasitic effects can help to realize the benefits of high speed switches (e.g., eGaN switches).

The figure of merit for a power switch can be determined according to equation 1: FOM=R _(DS(ON)) *Q _(G)  Eq. 1 where FOM is the figure of merit, R_(DS(ON)) is the on-resistance of the switch, and Q_(G) is the gate charge of the switch. The gate charge Q_(G) can be affected by parasitic inductances. Reducing the parasitic inductances can result in a lower FOM, a design improvement that is usually difficult to achieve.

It will be further appreciated that some, but not all, of the full advantages can be realized only by the simultaneous combination of sufficient parasitic effect reduction and component choices. For example, some advantages of reducing parasitic effects may not be realized if MOSFETs are used, under some circumstances. This is because, although parasitic effects may be reduced to a sufficient level to allow faster switching speeds, the MOSFET design may not allow for efficient switching at the faster speeds. Likewise, the full switching potential of eGaN switches (or other faster, and typically more costly switches) in a DC-DC converter can be limited by parasitic effects. Full switching potential can include more efficiently switching at higher frequencies in the megahertz range such as 1 MHz or higher, 3 MHz or higher, 4 MHz or higher, 5 MHz or higher, 7 MHz or higher, 10 MHz or higher, etc. In some instances, switching rates up to 15 MHz can be achieved, and switching rates outside these identified ranges could be used in some implementations.

Accordingly, an engineer testing limited techniques to reduce parasitic effects may not cause the parasitic effects to drop to an impactful level. An engineer testing a combination of parasitic reduction techniques may not achieve more significant gains if switching speeds are limited by MOSFETs. An engineer testing eGaN switches without first realizing and addressing the parasitic effects in DC-DC converters may not realize the switching speed benefits of using eGaN switches, especially because eGaN switches can be more costly than MOSFET switches. Additionally, increasing the switching speeds, especially to 1, 2, 3, 5, 7 or 10 MHz and above, depending on other variables, can go against conventional knowledge that efficiency tends to decrease with higher switching speeds.

The Integration and Chip Embedded Design section of the Detailed Disclosure discusses various embodiments for reducing parasitic effects and/or achieving faster switching speeds. Although some embodiments include a combination of features, the embodiments including fewer than all the features will still be appreciated in their own right.

Physical Arrangement Figures

FIG. 3 shows a cross section view 300 of an example chip embedded DC-DC converter. The view 300 includes insulators 301, conductor (e.g., metal) 303, bumps or pads 304, conductor micro-vias 305, a first PCB layer 307, conductive plating 309, a PCB core 311, traces 313, an embedded IC chip 315, a second PCB layer 317, an inductor 321, and a capacitor 323.

The embedded IC chip 315 can be embedded in a PCB core 311. In various embodiments, the IC chip 315 can be embedded in a layer of the PCB or between two or more layers of a PCB, or between a lower PCB and an upper PCB. The embedded IC chip 315 can include a PWM controller, driver, and/or one or more switches (e.g., eGaN switches), as discussed herein, such as with respect to FIG. 1. The embedded IC chip 315 can be coupled to the inductor 321 and capacitor 323 through a plurality of vias 305 and/or traces 313 in a DC-DC converter arrangement.

The insulators 301 can include, for example, a solder mask, mold, underfill, etc. The layers 307, 317 of the PCB can be a PCB substrate, laminate, resin, epoxy, insulator, etc. In the illustrated view 300 shown in FIG. 3, PCB core 311 can be a filler, laminate, an insulating mold compound or substrate, etc. The conductor (e.g., metal) 303, vias 305, and traces 313 can be metals or conductive materials of various types, such as copper, aluminum, gold, etc. Although the vias are shown as plated vias, some embodiments can use pillars or other vias. Various embodiments can use more or fewer types and layers of metals.

In some embodiments, the IC chip 315 can be flip chip mounted. In various embodiments, the IC chip 315 can be face up or face down such that connections on the IC chip 315 can be facing toward the inductor 321 and/or capacitor 323 or away from the inductor 321 and/or capacitor 323. If the connections on the IC chip 315 face away from the inductor 321 and/or capacitor 323, then the inductor 321 and/or capacitor 323 can be coupled by way of vias 305 and/or traces 313 to the far side of the IC chip 315.

Although FIG. 3 shows a single IC chip 315 that can include a driver and switches, in some embodiments, switches (e.g., monolithic eGaN switches) can be chip embedded in the PCB separate from the IC chip 315 and can be interconnected with the driver in the chip embedded IC chip 315. Vias, pads, and/or traces can couple various components as a DC-DC converter, and the two dies can be faced down or up. An inductor or other magnetic can be placed in or on the top layer and create a complete half bridge combination in a Buck converter or any other configuration using a Half Bridge scheme.

Although the IC chip 315 is shown coupled to the inductor 321 by way of both vias 305 and traces 313, in some embodiments, the IC chip 315 can be coupled to the inductor 321 and/or capacitor 323 by either vias 305 or traces 313 without the other. In various embodiments, the PCB assembly can have more or fewer PCB layers than shown in FIG. 3, and the IC chip 315 can be embedded in or between a single layer or multilayer PCB. In various embodiments, layers 307, 317 can be layers of a PCB or separate PCBs. The metal 303 exposed at the bottom of the PCB can provide input/output pads for coupling to an input power supply, a ground, and/or a load.

Parts of the inductor 321 and/or capacitor 323 can be stacked above the IC chip 315. In some embodiments, the inductor 321 and/or the capacitor 323 can be stacked entirely over the IC chip 315. The inductor 321 and IC chip 315 tend to be the larger components in the DC-DC converter package. In some embodiments, the smaller of the inductor 321 or IC chip 315 can be stacked within the footprint of the larger of the inductor 321 or IC chip 315. Although a single IC chip 315 that includes both switches and a driver is shown in FIG. 3, in various embodiments, the inductor 321 and/or capacitor 323 can overlap, at least partially, with components that are separate from the single IC chip 315. For example, the inductor 321 can overlap with one or more switches, with the PWM controller, and/or with the driver, etc.

The position of inductor 321 can contribute to better thermal performance of the DC-DC converter. By positioning the inductor 321 on top, the inductor 321 can be cooled by ambient air. The top-mounted inductor 321 also allows various sizes or shapes for the inductor 321 to be used (e.g., such that the inductor 321 is not constrained by the dimensions of the PCB).

FIG. 4A shows a perspective view 400 of an example chip embedded DC-DC converter with a stacked inductor 321. The inductor 321 can be stacked above an IC chip (not visible) that is embedded in a core 311 between the layers 317, 307 of a PCB. The inductor 321 can be coupled to the PCB, at least partially, through a metal contact 401. In some embodiments, one or more capacitors 323 (not visible) can be coupled to the PBC layer 317.

FIG. 4B shows a reverse perspective view 425 of an example rendered chip embedded DC-DC converter with a stacked inductor 321. The inductor 321 can be stacked above an IC chip (not visible) that is embedded between the layers 317, 307 of a PCB. The inductor 321 can be coupled to the PCB, at least partially, through a metal trace 313. One or more capacitors 323A, 323B can be coupled to the PBC layer 317. The one or more capacitors 323A, 323B can also be coupled to inductor 321 by way of a trace 313.

In some embodiments, as switching frequencies increase, inductors can be made smaller. Additionally, some materials and technologies such as thin film technologies can also reduce the sizes of inductors. Accordingly, in some embodiments the inductor can be embedded in a PCB, such as above or alongside an IC. Such arrangements offer further integration and increase the amount of space available, such as on a PCB mounting surface area, for other peripheral components, such as input and output capacitors.

FIG. 4C shows a side view 450 of an example chip embedded DC-DC converter with an embedded stacked inductor. A first layer 451 can be, for example, a packaging layer or a PCB layer. A second layer 453 can be a PCB layer that includes an inductor embedded within the second layer 453. A third layer 455 can be a PCB layer that includes an IC embedded within the third layer. The IC can include, for example, the PWM controller, driver, and/or switches (e.g., FET's). A fourth layer 457 can be, for example, a packaging layer or a PCB layer. In FIG. 4C, the inductor can overlap, at least partially, with the IC or be off to the side. The inductor can couple to the IC by way of vias and/or traces without bond wires.

FIG. 4D shows a side view 475 of an example chip embedded DC-DC converter with an embedded inductor. The layers 451, 453, 455, and 457 can be the same as or similar to those described for FIG. 4C. In FIG. 4D, layer 455 can include the IC and the inductor beside the IC. The IC can be coupled to the inductor by way of traces. Layer 453 can include embedded capacitors. In some embodiments, the one or more embedded capacitors can be embedded in the PDB, and the embedded capacitors can be mounted so that a footprint of the one or more embedded capacitors overlaps a footprint of the IC and/or inductor. In some embodiments, one or more embedded capacitors can be included in the same layer 455 with the embedded IC and/or embedded inductor. In some embodiments, capacitors can be surface mounted on layer 453. In some embodiments, layer 453 can be omitted. In some embodiments, capacitors can be mounted outside the PCB (e.g., such as capacitor 323 shown in FIG. 3).

FIG. 5 shows a see-through perspective view 500 of an example chip embedded DC-DC converter. FIG. 5 shows the same example chip embedded DC-DC converter as shown in FIG. 4A and FIG. 4B, but with without the inductor 321, capacitors 323, or core 311 to illustrate otherwise obscured components. Vias 305 can couple traces 313 and/or pads 303.

FIG. 6 shows a bottom view 600 of an example chip embedded DC-DC converter. FIG. 6 shows the same example chip embedded DC-DC converter as shown in FIG. 5. Exposed metal 303 pads between areas of insulator 301 provide electrical contacts for the supply voltage, ground, and/or voltage output. Vias 305 are shown. However, in some embodiments, the vias do not visibly extend through the exposed metal 303.

Reduced Footprint

The physical arrangement and other techniques disclosed herein can be used to reduce the footprint of a DC-DC converter. In some embodiments, the footprint can be reduced by about 70%. Stacked components, the use of smaller inductor with faster switching speeds, and a single package of components can all contribute to the reduced footprint.

As previously discussed, some DC-DC converter packages do not include an inductor or capacitor, and some DC-DC converters may include an inductor mounted beside a driver, PWM controller, and/or IC chip. Such packages may give a user the flexibility to select particular values for the capacitors and/or inductors and control the quality of those components. However, arranging components in a stacked arrangement instead of beside each other can reduce the footprint of the DC-DC converter. Some embodiments disclosed herein feature an inductor that is vertically stacked, wholly or partially, above the IC chip. Some embodiments disclosed herein feature a capacitor that is vertically stacked, wholly or partially, above the IC chip. Stacking the inductor and/or capacitor can reduce the footprint of the DC-DC converter. Stacked components can be electrically coupled (e.g., to the IC chip) with vias, which can reduce parasitic effects as discussed above. Some embodiments disclosed herein can provide for ease of design such that individual components do not need to be selected, arranged, and mounted by a user. A single package DC-DC converter can be used without configuring external capacitors or inductors. Furthermore, some embodiments can integrate the inductor into the package without compromising the size of the inductor, without compromising the performance of the inductor, and/or without requiring a custom made inductor.

As discussed above, the parasitic effects can be reduced, and the switching speed of the DC-DC converter can be increased with efficiency. The inductance of a DC-DC converter can be determined according to equation 2,

$\begin{matrix} {L = \frac{\left( {{Vin} - {Vo}} \right)*{Vo}}{2\;\Delta\; i\; L*{Fs}*{Vin}}} & {{Eq}.\mspace{14mu} 2} \end{matrix}$

where L is the inductance, V_(in) is the input voltage, V_(o) is the output voltage, ΔiL is the inductor ripple current, and F_(s) is the switching frequency. Notably, the inductance decreases as the switching speed increases. Accordingly, reduced parasitic effects and faster one or more switches (e.g., eGaN switches) can allow the DC-DC converters to use smaller inductors. In DC-DC converters, inductors can be one of the largest components. By reducing the size of the inductor (e.g., to a fraction of its original size), the footprint can be substantially reduced.

Some DC-DC converters include multiple packages. For example, there might be a first package that includes a driver, a second package for switches, and a third package that includes an inductor. Some embodiments disclosed herein feature a single package that includes all of the components of a DC-DC converter, such as a PWM controller, driver, switches (e.g., eGaN switches), inductor(s), and capacitor(s). In some embodiments disclosed herein, a number of components can be integrated into a single IC, such as the PWM controller, driver, and/or switches (e.g., eGaN switches).

Accordingly, the features relating to higher switching speeds can additionally synergize with the physical design of a DC-DC converter such that the size of a DC-DC converter can be reduced. The smaller DC-DC converter can be used in various applications to provide higher current density to power modern electronic devices such as microprocessors, field programmable gate arrays, application specific integrated processors, etc. Smaller DC-DC converters can be made at reduced manufacturing costs. The techniques disclosed herein can reduce board and package parasitic effects. Smaller DC-DC converters can feature tighter connections that reduce parasitic effects between the inductor, the IC chip, and/or a load, and the DC-DC converter can be efficiently operated at higher frequencies. The techniques disclosed herein can lead to reduced noise, including lower ripple effects and lower electromagnetic interference.

Generally, a larger sized DC-DC converters can handle larger amounts of current. In some embodiments, the DC-DC converters disclosed herein can handle a given amount of current with a smaller sized DC-DC converter, as compared to conventional approaches. For example, the DC-DC converters disclosed herein can have a footprint area of less than 20 mm² per amperage of current, less than 15 mm² per amperage of current, less than 10 mm² per amperage of current, less than 7 mm² per amperage of current, less than 5 mm² per amperage of current, less than 4 mm² per amperage of current, less than 3 mm² per amperage of current, less than 2 mm² per amperage of current, less than 1.5 mm² per amperage of current, or less than 1 mm² per amperage of current. The DC-DC converters can have as low as 1.0 or 0.5 mm² per amperage of current, although values outside the ranges discussed herein can be used in some implementations.

Example Applications

The DC-DC converters disclosed herein can be used to provide power to electronic devices. Examples include using the DC-DC converter to convert a primary supply voltage into a DC voltage appropriate for electronic devices powered through the supply voltage. By way of example, in some applications, modern power management solutions can use 40 or more chip embedded DC-DC converters to power 40 or more electronic components while meeting specifications for size, input/output ripple, efficiency, and thermal limits. DC-DC converters as disclosed herein can be made smaller and used in modern systems where the space and board size are limited. DC-DC converters as disclosed herein can be used to power components in various market segments such as storage, servers, networking, telecom, internet of things, etc. Other applications include using the DC-DC converters disclosed herein to provide power to micro point of load devices such as for processors in blade servers, components of solid state devices, etc.

FIG. 7A shows an example of a DC-DC converter used in a memory device 700. The memory device 700 can be, for example, a solid state drive. The memory device 700 can include a controller 703 and a plurality of memory chips 705 coupled through a PCB 701. A DC-DC converter 707 can receive a supply voltage through power input pins 709 and provide DC power to the memory chips 705 and/or controller 703. The DC-DC converter 707 can be coupled to an inductor 709 by way of bond wires or traces 711 through the PCB 701. The PCB 701 can be a separate PCB 701 from the package of the DC-DC converter 707. The capacity of the memory device 700 is limited by the number of memory chips 705, which is six memory chips in the implementation of FIG. 7A.

FIG. 7B shows an example application of a chip embedded DC-DC converter to a memory device 750. A chip embedded DC-DC converter 751 receives a supply voltage through power input pins 709 and provide DC power to the memory chips 705 and/or controller 703. A smaller inductor can be included in the package footprint of the chip embedded DC-DC converter 751. The chip embedded DC-DC converter 751 can be substantially smaller than the DC-DC converter 707 of FIG. 7A. Accordingly, the additional PCB room can be used for an additional memory chip 753 to improve the memory capacity of the memory device 750.

FIG. 8A shows an example application of DC-DC converters on a circuit board 800. The circuit board 800 can be, for example, a blade server or motherboard that includes a plurality of power connectors 801 (PWR), a voltage regulator management (VRM) circuit 803, a plurality of random access memory (RAM) slots 805, a plurality of peripheral component interconnect express (PCIE) slots 813, and a rear input/output panel 815. The circuit board 800 also includes a plurality of DC-DC converters 807 at points of load. The DC-DC converters 807 each power one of the central processing units 809 or computer chips 811. The DC-DC converters 807 can receive power supplied through the power connectors 801 and/or VRM circuit 803 and convert the voltage of the supplied power into a DC voltage meeting the DC power specifications of each respective CPU 809 or computer chip 811.

FIG. 8B shows an example application of chip embedded DC-DC converters on a circuit board 850. The circuit board 850 includes a plurality of chip embedded DC-DC converters 851 (e.g., at points of load). The chip embedded DC-DC converters 851 can power central processing units 809 and/or computer chips 811, for example. The DC-DC converters 851 can receive power supplied through the power connectors 801 and/or VRM circuit 803 and convert the voltage of the supplied power into a DC voltage meeting the DC power specifications of the respective CPUs 809 and/or computer chips 811. The chip embedded DC-DC converters 851 can be smaller than the DC-DC converters 807 of FIG. 8A. Accordingly, the motherboard can have room for additional computer chips 853. Areas previously occupied by the DC-DC converter 807 may now be open areas 855 available for other components or can be left open to improve airflow.

Additional Embodiments

In some example embodiments, one or more switches (e.g., eGaN switches) (e.g., monolithic or standalone) can be used in a chip embedded DC-DC synchronous buck converter with an inductor where the embedded IC chip includes a PWM controller and a driver. In comparison to a MOSFET based DC-DC synchronous buck converter, the chip embedded DC-DC converter can be switched at higher speeds with lower switching losses, can switch more efficiently at high switching speeds (e.g., around 5 MHz or at other speeds described herein), and the eGaN switches can have about five times lower Q_(G).

Some embodiments realize improved efficiency gains of about 30% lower power losses in comparison to alternative designs when switching at the same speeds, such as 3 MHz.

An example embodiment of a chip embedded DC-DC converter can be packaged in about a 3×3×1.5 mm package, switch at ranges from about 1-5 MHz, and supply about 6 A of current. In comparison, various wire-bond DC-DC converter designs for similar amperage can be about 12×12 mm in area and switch at about 600 kHz.

An example embodiment of a chip embedded DC-DC converter can receive a 12 V power supply and output a DC signal that is about 1.2 V and about 10 A. The chip embedded DC-DC converter can switch at about 1 MHz and include an inductor that is about 300 nH.

Some example embodiments of a chip embedded DC-DC converter include 25 A buck converters that can fit in package that is about 6×6 mm or 7×7 mm.

Some embodiments of chip embedded DC-DC converters include eGaN switches. The switches can operate at about 5 MHz, and the chip embedded DC-DC converters can operate with efficiency similar to MOSFET based DC-DC converters operating at about 1 MHz. This can result in smaller package sizes and overall higher system performance due to faster responses to transient loads.

Example Method

FIG. 9 shows a flowchart of an example method 900 for making and using a chip embedded DC-DC converter.

At block 901, an integrated circuit can be fabricated. The integrated circuit can be an IC chip that includes at least one of: a driver, a PWM controller, and one or more power switches. The IC chip can include a plurality of: a driver, a PWM controller, power switches, an inductor, a capacitor, or other component of a DC-DC converter. In some embodiments, the one or more power switches can be eGaN switches, gallium arsenide switches, or other types of high performance switch.

At block 903, a first PCB part can be formed. Forming the first PCB part can include providing a PCB layer or insulator, masking, etching, drilling vias, filling vias, depositing conductive traces and pads, providing some or all of the I²C and/or PMBUS, and the like.

At block 905, the IC chip can be embedded using chip embedded technology. In some embodiments, a cavity could be formed (e.g., in a PCB), for example using machining or etching techniques, and the IC chip could be placed into the cavity. The IC chip can be coupled to the first PCB part, into a PCB, on a PCB layer, between multiple PCB layers, between multiple PCBs, etc. The IC chip can be chip embedded face up or face down. In some embodiments, the IC is embedded using a flip chip technique. The IC chip or die can be coupled to a die attachment or bonding material. In some embodiments, other components can also be embedded in the PCB. For example, in embodiments where one or more switches (e.g., monolithic eGaN power switches) are separate from the IC chip, the one or more switches (e.g., monolithic eGaN switches) can also be embedded in the PCB.

At block 907, the insulators and conducive routing for a second part of the PCB can be formed. This can include providing an additional PCB layer or insulator, masking, etching, drilling or exposing vias, filling vias, depositing conductive traces and pads, providing some or all of the I²C and/or PMBUS, and the like. In some embodiments, the actions described with respect to blocks 903, 905, and 907 be integrated together and/or overlap. In blocks 903, 905, and 907, the conductors (e.g., vias and traces) can be formed to couple components in a DC-DC converter arrangement (e.g., as shown in FIG. 1 and FIG. 3).

At block 909, an inductor can be coupled. The inductor can be coupled to the top of the PCB. The inductor can be stacked, at least partially, with one or more of the other components of the DC-DC converter such as the IC chip. The inductor can be stacked, at least partially, with one or more of the other components of the DC-DC converter such as the PWM controller, driver, and switches. In some embodiments, other surface components such as capacitors can also be coupled. Accordingly, the components of a chip embedded DC-DC converter can be coupled together. In some embodiments, the inductance of the inductor can be selected based at least in part on an overcurrent limit, for example, as described with respect to FIG. 1. In some embodiments, an overcurrent limit can be determined, adjusted, and/or trimmed based at least in part on a saturation limit of the inductor. In some embodiments, the inductor and overcurrent limit values can be determined and/or designed by a single person, designer, design team, and/or manufacturer.

At block 911, the chip embedded DC-DC converter can be packaged. This can include packaging the chip embedded DC-DC converter as a single discrete component. The package can include the inductor and capacitor such that the DC-DC converter can operate without external inductors or capacitors.

At block 913, a load can be coupled to the DC-DC converter. This can include, for example, coupling an output of the packaged chip embedded DC-DC converter through a trace on a separate motherboard to an electronic device. In some embodiments, the DC-DC converter can be coupled near the point of load to reduce some parasitic effects.

At block 915, a power supply can be coupled to the packaged chip embedded DC-DC converter. Accordingly, the chip embedded DC-DC converter can use the supplied power to provide a DC output voltage to power the electronic device.

Although blocks 911, 913 describe packaging and using the packaged chip embedded DC-DC converter with a separate PCB of a load device, in some embodiments, the techniques described herein can be applied to the end-device PCB.

Multi-Inductor Chip Embedded DC-DC Converter

The chip embedded DC-DC converter technology described herein can be extended to multi-inductor implementations. This can include, for example, dual buck converters, dual boost converters, and voltage converters with 2, 3, 4, 5, 6, 8, 16, or any number of inductors. The multiple inductors can be arranged in parallel. The output of the multiple inductors (e.g., in parallel arrangement) can be coupled to an energy storage circuit such as a capacitor or LC resonant circuit. Each respective inductor can be coupled to a respective pair of switches. Each respective pair of switches can be driven by a respective driver. Each driver can be driven with PWM signals that are out of phase with PWM signals provided to the other drivers. Each PWM signal can have an on time that is a small enough fraction of a shared period such that the superimposed combination of driver signals has an effective period that is shorter than the shared period. In some embodiments, the multi-inductor chip embedded DC-DC converter can be formed by duplicating some or all of the components (e.g., the switches, the inductor, parts of the integrated circuit) disclosed herein (e.g., shown in FIG. 1).

The various embodiments disclosed herein can have one, some combinations, or all of the following features. Multi-inductor chip embedded DC-DC converters can operate faster and more efficiently than single inductor chip embedded DC-DC converters. The current through the DC-DC converter can be divided among the multiple inductors. The heat can be spready out over multiple inductors. Smaller sized individual inductors can be used. The current density can be increased. The overall size of the DC-DC converter can be reduced. Switches can switch fewer numbers of times. The life expectancies of the switches can be extended. The life expectancies of the inductors can be improved. Fewer and/or smaller number of output capacitors can be used. There can be a faster transient response. There can be a lower fluctuation in output voltage when current demand changes. The DC-DC converter can operate at higher frequencies and/or use smaller inductors (e.g., in accordance with Eq. 2). The size of the DC-DC converter can be reduced. Each pair of switches can operate at a maximum frequency that is efficient, yet the overall frequency can be greater than the individual frequency of any pair of switches.

In some embodiments, power losses can be reduced. Using the equation P=I²*R, it can be seen that power loss increases with DC current (I). However, by splitting the current among multiple inductors, the overall power loss can be reduced. Furthermore, the resistance of each inductor also decreases. For example, by dividing the current (I_(o)) among two inductors, P=2*[(I_(o)/2)²*R/2]=[I_(o) ²*R]/2, it can be seen that power loss can be reduced by half. Accordingly, the distributed power delivery among multiple inductors provides improved efficiency. As demand for high current density DC-DC converters increases, multi-inductor, chip embedded DC-DC converters can provide small sizes and high current densities with less power loss.

In some embodiments, the smaller inductors in a multi-inductor, chip embedded DC-DC converter allows for faster transient responses to changes in the demanded current. For example, as shown in FIG. 8B, a chip embedded DC-DC converter may provide DC power to a CPU. The CPU may suddenly experience a heavy computational load (e.g., utilize all cores and/or boosting its switching frequency), causing a sudden increase in the power drawn (e.g., scaling from 1 amp to 10 amps in the ns range). As energy is drawn from an output capacitor (e.g., output capacitor 111 of FIG. 1, FIG. 2), the voltage across the output capacitor may fall too fast beyond the DC power specifications (e.g., <1% drop in voltage) required by the CPU, risking stop errors. Accordingly, a feedback system (e.g., as shown in FIG. 14, FIG. 16, and FIG. 17) may be implemented to increase the power delivered through the inductor to the capacitor and prevent the voltage drop. However, a high inductance resists the change in power delivery. Because a multi-inductor system uses smaller inductors, the transient feedback response of a multi-inductor, chip embedded DC-DC converter can be faster than the transient feedback response of a DC-DC converter with fewer, larger inductors, and the response can have a lower output voltage drop. The DC-DC converters disclosed herein that have higher switching frequencies can utilize smaller inductors, so that the single-inductor embodiments described herein can have improved response to transient loads.

Example Dual Buck Converters

FIG. 10 shows an example dual inductor design for a dual buck converter 1000 using a chip embedded DC-DC converter. A dual buck converter can use two parallel inductors instead of using a single inductor.

FIG. 10 includes a first inductor 1001, a second inductor 1003, and a PCB 1005 that includes a chip embedded IC and other components (shown in FIGS. 11A, 11B, 11C and 11D, not visible in FIG. 10). A first input node 1007A to the first inductor 1001 can correspond to a first pad 1007B on the PCB 1005. A second input node 1009A to the second inductor 1003 corresponds to a second pad 1009B on the PCB 1005. A voltage output node can 1011A correspond to a voltage output pad 1011B on the PCB 1005. A graph 1013 shows the waveforms for Signal 1, Signal 2, and the Output Signal.

The dual buck converter can be configured to include two inductors 1001, 1003. The two inductors 1001, 1003 can be surface mounted on the PCB 1005. In various embodiments, the two inductors 1001, 1003 can be two separate inductors positioned side by side, two separate inductors vertically stacked on top of the other, or it a single magnetic core with two inductor windings.

Signal 1 is provided to the first input node 1007A. Signal 1 has a period of T. Signal 2 is provided to the second input node 1009A. Signal 2 also has a period of T. Signals 1 and 2 are out of phase with each other and have an “on” time that is less than 50% of the period T. An Output Signal is formed by the combination of Signal 1 and Signal 2. For each pulse, the output signal has the same “on” time as Signal 1 and Signal 2. The “on” times of Signal 1 and Signal 2 are the same, and the effective period of the Output Signal is reduced by half (the frequency is doubled).

FIG. 12 shows an example circuit level schematic 1200 of a dual buck converter including a chip embedded DC-DC converter. The schematic includes a voltage source 1201, a first switch 1203 of a first switch pair, a second switch 1205 of the first switch pair, a third switch 1207 of a second switch pair, a fourth switch 1209 of the second switch pair, a first inductor 1211, a second inductor 1213, an output capacitor 1217, and a voltage output node 1219.

The pair 1215 of inductors 1211, 1213 can be coupled outside of the PCB. The switches 1203, 1205, 1207, 1209 can be embedded in the PCB, either as standalone chips or as part of an IC chip that includes other components (e.g., a driver, PWM controller, other switches). The capacitor 1217 can be coupled outside of the PCB or inside of the PCB.

The voltage source 1201 can be coupled to a drain of the first switch 1203. The source of the first switch 1203 can be coupled to a first node of the first inductor 1211. The source of the first switch 1203 can also be coupled to a drain of the second switch 1205. The gates of the first switch 1203 and the second switch 1205 can be coupled to a driver (not shown in FIG. 12). The driver can drive opposite control signals to the first switch 1203 and the second switch 1205, turning the first switch 1203 and the second switch 1205 on and off in alternation, such that one of the first switch 1203 and the second switch 1205 is on while the other one is off. While the first switch 1203 is on and the second switch 1205 is off, energy can be provided from the voltage source 1201 to the inductor 1211 and/or capacitor 1217, where the energy can be stored, causing the output voltage to rise. While the first switch 1203 is off and the second switch 1205 is on, energy can be drained from the inductor 1211 and/or capacitor 1217, causing the output voltage to fall.

The voltage source 1201 can be coupled to a drain of the third switch 1207. The source of the third switch 1207 can be coupled to a first node of the second inductor 1213. The source of the third switch 1207 can also be coupled to a drain of the fourth switch 1209. The gates of the third switch 1207 and the fourth switch 1209 can be coupled to a driver (not shown in FIG. 12). Accordingly, the driver can drive opposite control signals to the third switch 1207 and the fourth switch 1209, turning the third switch 1207 and the fourth switch 1209 on and off in alternation, such that one of the third switch 1207 and the fourth switch 1209 is on while the other one is off. While the third switch 1207 is on and the fourth switch 1209 is off, energy can be provided from the voltage source 1201 to the inductor 1213 and/or capacitor 1217 where the energy can be stored, causing the output voltage to rise. While the third switch 1207 is off and the fourth switch 1209 is on, energy can be drained from the inductor 1213 and/or the capacitor 1217, causing the output voltage to fall.

The second node of the first inductor 1211 and the second node of the second inductor 1213 can be coupled to the output node 1219 and also coupled to the output capacitor 1217, also referred to as a smoothing capacitor. The voltage at the output node 1219 can be affected by the energy stored in the capacitor 1217. The energy stored in the capacitor 1217 can increase when current flows from the capacitor 1217 from either the second node of either the first inductor 1211 or the second node of the second inductor 1213. Accordingly, a small signal ripple is provided to the capacitor as the switches provide or discharge energy.

The first pair of switches 1203, 1205 can be driven out of phase from the second pair of switches 1207, 1209. The first pair of switches 1203, 1205 can also be driven at the same frequency and with the same period as the second pair of switches 1207, 1209. Accordingly, in some embodiments, at most one of the upper switches 1203, 1207 will be on at a given time. The four switches 1203, 1205, 1207, 1209 can be driven with four respective signals that are all out of phase with each other. The first pair of switches 1203, 1205 and the first inductor 1211 provide DC bucking functionality in parallel with the second pair of switches 1207, 1209 and the second inductor 1213.

FIG. 13A shows an example circuit level schematic 1300 of a DC-DC converter including a chip embedded DC-DC converter. The components of FIG. 13A can be the same as or similar to those in FIG. 12. The DC-DC converter of FIG. 13A can include an additional capacitor 1221. The capacitor 1221 can store energy when switch 1203 is turned on. In some embodiments, energy can be stored such that the capacitor 1221 charges to about half the voltage of the voltage supply 1201. When switch 1203 is turned on, switch 1207 is turned off, and switch 1205 is turned off, transient current can flow through the capacitor 1221 to inductor 1211. When switch 1207 is turned on and switch 1209 is turned off, the capacitor 1221 can provide power to switch 1207 and cause current to flow to inductor 1213. Capacitor 1221 also acts as an AC coupling capacitor between switch 1207 and switch 1205. The components in FIG. 13 are also arranged with a modified layout compared to those in FIG. 12, however, the DC-DC converters in FIG. 12 and FIG. 13A can function similarly.

FIG. 13B shows an example circuit level schematic 1350 of a DC-DC converter including a chip embedded DC-DC converter. The components of FIG. 13 can be the same as or similar to those in FIG. 12. The first pair of switches 1203, 1205 and first inductor 1211 can be coupled to a first capacitor 1217A and configured to provide a first output voltage at a first output node 1219A. The second pair of switches 1207, 1209 and second inductor 1213 can be coupled to a second capacitor 1217B and configured to provide a second output voltage at a second output node 1219B. The output voltages at the first and second output nodes 1219A, 1219B can be the same voltage or can be different voltages. In some embodiments, a driver (e.g., as shown in FIG. 1, not shown in FIG. 13B) can separately drive the first pair of switches 1203, 1205 and second pair of switches 1207, 1209 such that different voltages are provided at the different nodes 1219A, 1219B.

Example Designs for Chips Embedded in Dual Buck Converters

FIG. 11A shows a first example layout design 1100 for the embedded chip in a dual buck converter. The design includes an IC section 1101, a first power switch 1103 of a first switch pair, a second power switch 1105 of the first switch pair, a third power switch 1107 of a second switch pair, and a fourth power switch 1109 of the second switch pair.

In the embodiment of FIG. 11A, the IC section 1101, the first power switch 1103, the second power switch 1105, the third power switch 1107, and the fourth power switch 1109 are all included in the same IC chip. The IC section 1101 can include a PWM controller and a driver. The driver can be configured to drive the first switch pair out of phase with the second switch pair. The driver can be configured to drive the first switch pair and the second switch pair with the same period and the same frequency. The driver can also be configured to drive the switches in each switch pair in alternation. In some embodiments, the IC section 1101 includes a first driver configured to drive the first switch pair and a second driver configured to drive the second switch pair. The PWM controller can provide first PWM signals to the first driver and second PWM signals to the second drivers, and the first and second PWM signals can be out of phase with each other.

FIG. 11B shows a second example layout design 1120 for embedded chips in a dual buck converter. The design includes an IC chip 1121, a first power switch 1123 of a first switch pair, a second power switch 1125 of the first switch pair, a third power switch 1127 of a second switch pair, and a fourth power switch 1129 of the second switch pair.

The first power switch 1123 and the second power switch 1125 can be part of a first monolithic switch chip, such as a monolithic eGaN switch chip. The third power switch 1127 and the fourth power switch 1129 can part of a second monolithic switch chip. In some embodiments, the first monolithic switch pair and the second monolithic switch pair can be part of the same monolithic chip. In some embodiments, the first monolithic switch pair and the second monolithic switch pair can be separate monolithic chips. The IC chip 1121 and the separate monolithic chips can be embedded in a PCB. The IC section 1121 can include a PWM controller and a driver. The driver can be configured to drive the first monolithic switch pair out of phase with the second monolithic switch pair. The driver can be configured to drive the first monolithic switch pair and the second monolithic switch pair with the same period and the same frequency. The driver can also be configured to drive the switches in each monolithic switch pair in alternation. In some embodiments, the IC section 1121 includes a first driver configured to drive the first monolithic switch pair and a second driver configured to drive the second monolithic switch pair. The PWM controller can provide first PWM signals to the first driver and second PWM signals to the second drivers, and the first and second PWM signals are out of phase with each other.

FIG. 11C shows a third example layout design 1140 for embedded chips in a dual buck converter. The design includes an IC chip section 1141, a first power switch 1143 of a first switch pair, a second power switch 1145 of the first switch pair, a third power switch 1147 of a second switch pair, and a fourth power switch 1149 of the second switch pair.

The IC chip section 1141, the first power switch 1143 and the third power switch 1147 can be part of a first IC chip. The second power switch 1145 and the fourth power switch 1149 can be separate chips, such as separate monolithic eGaN chips, from the first IC chip. In some embodiments, the second power switch 1145 and the fourth power switch 1149 can be part of the same monolithic chip. One, some, or all of the chips can be embedded in the PCB. The IC section 1141 can include a PWM controller and a driver. The driver can be configured to drive the first switch pair out of phase with the second switch pair. The driver can be configured to drive the first switch pair and the second switch pair with the same period and the same frequency. The driver can also be configured to drive the switches in each switch pair in alternation. In some embodiments, the IC section 1141 includes a first driver configured to drive the first switch pair and a second driver configured to drive the second switch pair. The PWM controller can provide first PWM signals to the first driver and second PWM signals to the second drivers, and the first and second PWM signals are out of phase with each other.

FIG. 11D shows a fourth example layout design 1160 for embedded chips in a dual buck converter. The design includes an IC chip section 1161, a first power switch 1163 of a first switch pair, a second power switch 1165 of the first switch pair, a third power switch 1167 of a second switch pair, and a fourth power switch 1169 of the second switch pair.

The IC chip section 1161, the first power switch 1163, the second power switch 1165, the third power switch 1167, and the fourth power switch 1169 can be parts of separate IC chips. One, some, or all of the separate IC chips can be embedded in a PCB. The IC section 1161 can include a PWM controller and a driver. The driver can be configured to drive the first switch pair out of phase with the second switch pair. The driver can be configured to drive the first switch pair and the second switch pair with the same period and the same frequency. The driver can also be configured to drive the switches in each switch pair in alternation. In some embodiments, the IC section 1161 includes a first driver configured to drive the first switch pair and a second driver configured to drive the second switch pair. The PWM controller can provide first PWM signals to the first driver and second PWM signals to the second drivers, and the first and second PWM signals are out of phase with each other.

Various additional arrangements are possible, such that any combination of components 1161, 1163, 1165, 1167, and 1169 can be combined into any number of IC chips. In some embodiments, a multi inductor DC-DC converter can be created by combining individual packages of individual or multi inductor DC-DC converters.

Additional Example Features of Multi-Inductor Chip Embedded DC-DC Converters

In some chip embedded DC-DC converters, the inductor is the largest physical component. A multi-inductor chip embedded DC-DC converter can instead use multiple, smaller inductors coupled in parallel. Switches can be driven out of phase such that the multiple inductors charge and discharge energy out of phase. In some embodiments, the outputs of the multiple inductors are coupled in parallel such that the output ripple of the multiple inductors is at a higher frequency than the output ripple of any individual inductor. In some embodiments, the outputs of the multiple inductors are coupled in parallel, and the output ripple of the multiple inductors has the same period as the output ripple of the individual inductors.

The output ripple frequency of multiple inductor DC-DC converters can be higher, and the number and/or capacitance of the output capacitor(s) can be reduced, and smaller output capacitor(s) can be used, in some embodiments.

As described above, the multiple inductor system can have a higher effective switching speed as compared with a single inductor system. In some embodiments, this can be done without increasing the switching speed of the switches; instead, multiple switches can operate out of phase with each other. Accordingly, a higher effective switching speed can be reached without pushing individual switches to higher, inefficient switching speeds.

In accordance with Eq. 2, due to higher effective switching speed of the multiple inductors arranged in parallel, the inductance of the multiple inductors can be decreased. Accordingly, the inductors can be arranged in parallel to lower the inductance, and/or smaller inductors with smaller inductances can be used. Because smaller inductors can be used, the overall DC-DC converter size can be reduced, especially if the inductor(s) is (are) the largest component.

In some embodiments, further synergy can result from using smaller inductors: the switching speeds of the switches can increase because the inductance load of the switches is reduced. This can lead to faster efficient switching speeds, further lowering the inductance according to Eq. 2, and so on.

In some embodiments, a multi-inductor chip embedded DC-DC converter can use a smaller output capacitor as compared to the output capacitor in a single inductor DC-DC converter.

Examples of Chip Embedded DC-DC Converter with Feedback

FIG. 14 shows an example chip embedded DC-DC converter 1400 with an external ripple voltage feedback circuit. The chip embedded DC-DC converter 1400 can include an embedded IC chip 1403 that can include a driver and/or modulator, as discussed herein. The IC chip can be embedded in a PCB 1401. The chip embedded DC-DC converter 1400 also includes a first power switch 1405, a second power switch 1407, and an inductor 1409. The inductor 1409 is schematically represented to show its inductance component 1411 and its internal direct current resistance (DCR) component 1413.

The chip embedded DC-DC converter 1400 receives an input voltage at a voltage input node 1415 and provides an output voltage at an output voltage node 1417. An output capacitor 1421 is coupled to the output node 1417, and the output capacitor is schematically represented to show its capacitive component 1423 and its equivalent series resistance (ESR) 1425. A feedback path 1427 is coupled from the output node to the embedded IC chip 1403.

The chip embedded DC-DC converter 1400 can receive the input voltage and can generate the output voltage as previously described herein. The output voltage can have small fluctuations, or ripples, as the switches turn on and off. The ripple voltage (V_(ESR)) can be calculated by multiplying the inductor current I_(L) by the ESR. The feedback path 1427 senses the ripples and/or DC output voltage. A feedback indication of the ripple and/or DC output voltage is provided to the embedded IC chip 1403. The modulator in the embedded IC chip 1403 can use the feedback to control the switches 1405, 1407 to decrease the output voltage if the output voltage is too high, and to increase the output voltage if the output voltage is too low.

Feedback systems can use current mode control schemes and voltage mode control schemes to ensure DC-DC operational stability over a wide range of duty cycles. In current mode control schemes, a slope compensation scheme can be used and implemented with external components that may add to increased size and cost. Current mode control schemes may use type II compensation for loop stability and may have slower loop responses. In voltage mode control schemes, a voltage error can be amplified, fed back, and compensated for.

In some embodiments, the modulator can use a constant on time frequency modulation scheme, a constant off time frequency modulation scheme, a pulse width modulation scheme, or other scheme. Constant on time and constant off time schemes can provide for stable DC-DC operation with high performance. In some embodiments, it can be desirable for the modulator to detect the ripple voltage to trigger certain control events. For example, in a constant on time scheme or constant off time scheme, the modulator can detect the AC ripple in order to generate an on or off pulse with a constant on or off time respectively, thereby modulating the frequency and affecting the periods of the control signals sent to switches 1405, 1407. For example, in a constant on time scheme, an on pulse of a fixed width can be provided to increase the output voltage in response to detecting a low output voltage in comparison to a reference voltage and/or in response to detecting a sufficient amount of inductor current ripple. Accordingly, for a constant on time scheme, each pulse has the same duration in the on state, and the modulation is achieved by performing more or fewer pulses per time (e.g., the off time between pulses would vary). A constant off time scheme can be similar to the constant on time scheme described herein, except that the off time between pulses is constant, and the modulation can be achieved by width of the on pulses. In another example voltage mode system, a frequency can be fixed, and the duty cycle of the pulse can be modulated. Variations can include leading or trail edge modulation schemes. Any suitable modulation scheme can be used. Accordingly, the ESR 1425 can be designed and/or selected such that a sufficiently large V_(ESR) can be detected by the modulator.

Some embodiments disclosed herein provide solutions to a number of conflicting design challenges. Non-delayed feedback paths can provide fast responses to changes in output voltage. Feedback paths can be used in some modulation/control schemes, such as constant on time or constant off time schemes, to control when the switches 1405, 1407 are turned on or off. To provide a measurably large V_(ESR) signal along the feedback path that is reliably detectable by the modulator, the ESR 1425 of the capacitor 1421 can be designed and/or selected such that a sufficiently large ripple is caused. At the same time, it can be desirable to minimize the ripple voltage. A DC-DC converter can ideally generate a pure DC voltage. In practice, many applications allow small ripples on the output of a DC-DC converter but only within a small margin. Some devices powered by a DC power supply may require a maximum of 3% ripple, 2%, ripple 1% ripple, 0.5% ripple, 0.1% ripple, 0.05% ripple, 10 mV ripple, 5 mV ripple, 3 mV ripple, 1 mV ripple, 0.5 mV ripple, a smaller amount of ripple, or an undetectably low amount of ripple, or any ranges bounded by any of these values, although in some instances values outside these ranges can be used. For example, some point of load devices may specify that a DC power supply provide a 1.00 V DC output with no more than 1% (10 mV) ripple or variation from the 1.00 V value. A very low ESR capacitor can be used to achieve low ripple output. However, if the ripple is too low, then the modulator might not work based on the ripple feedback (e.g., the modulator might not distinguish ripple from noise, might operate erratically, etc.).

The disclosure herein includes some embodiments of DC-DC converters that use a ripple-triggered modulator, low ESR capacitors, and provide a low-ripple DC output.

Example Current and Ripple Graphs

FIG. 15 shows example graphs 1500, 1550 of inductor current I_(L) over time and equivalent series resistance voltage V_(ESR) (also referred to as ripple voltage) over time. The line 1501 indicates current I_(L) through the inductor 1409 of FIG. 14. The line 1551 indicates the output ripple voltage V_(ESR) at node 1417 of FIG. 14.

The inductor current I_(L) increases when switch 1405 is turned on and switch 1407 is turned off. I_(L) increases according to the equation:

$\begin{matrix} {I_{Lon} = {{\frac{V_{i\; n} - V_{out}}{L}*T_{on}} + I_{o}}} & {{{Eq}.\mspace{14mu} 3}A} \end{matrix}$ where V_(in) is the input voltage, V_(out) is the output voltage, L is the inductance, T_(on) is the amount time that switch 1405 is turned on, and I_(o) is an initial current.

The inductor current I_(L) decreases when switch 1405 is turned off and switch 1407 is turned on. I_(L) decreases according to the equation:

$\begin{matrix} {I_{Loff} = {{\frac{- V_{out}}{L}*T_{off}} + I_{o}}} & {{{Eq}.\mspace{14mu} 4}A} \end{matrix}$ where V_(out) is the output voltage, L is the inductance, T_(off) is the amount time that switch 1405 is turned off, and I_(o) is an initial current. Equations 3 and 4 are the applied version of the general equation, V=L(dI/dt), where V is the voltage across an inductor, dI/dt is the rate of change in current with respect to time.

Based on equations 3A and 4A, the rates of change in the current can be determined by time derivatives such that:

$\begin{matrix} {{\frac{d}{d\; t}I_{Lon}} = \frac{V_{i\; n} - V_{out}}{L}} & {{{Eq}.\mspace{14mu} 3}B} \end{matrix}$

$\begin{matrix} {{\frac{d}{d\; t}I_{Loff}} = \frac{- V_{out}}{L}} & {{{Eq}.\mspace{14mu} 4}B} \end{matrix}$

V_(ESR) fluctuates up and down with the inductor current I_(L). However, V_(ESR) and I_(L) increase and decrease with different slew rates (e.g., with different slopes). The difference in rates is affected by the ESR of the capacitor 1421. The voltage can be determined by multiplying the inductor current I_(L) by the ESR according to the equation V=I*R_(ESR). Accordingly,

$\begin{matrix} {{\frac{d}{d\; t}V_{Lon}} = {\frac{V_{i\; n} - V_{out}}{L}*R_{ESR}}} & {{{Eq}.\mspace{14mu} 3}C} \end{matrix}$

$\begin{matrix} {{\frac{d}{d\; t}V_{Loff}} = {\frac{- V_{out}}{L}*R_{ESR}}} & {{{Eq}.\mspace{14mu} 4}C} \end{matrix}$

As shown in the graphs 1500, 1550, as the current I_(L) increases and decreases, the V_(ESR) also increases and decreases at the same time, but at different slew rates (different slopes). The slew rate of V_(ESR) is proportional to and affected by the ESR according to the equation V_(ESR)=I_(L)*ESR. Accordingly, for low ESR values, the V_(ESR) may have a small amplitude, even if I_(L) is large. For example, the inductor current I_(L) is 3.0 A with a 50% ripple so that it fluctuates from 1.5 A to 4.5 A with an amplitude of 3.0 A. If a low ESR is 1 mΩ, then the V_(ESR) may fluctuate between −1.5 mV to 1.5 mV, which can be too small and/or difficult for some modulators to reliably use. Also, the V_(ESR) alternates between positive and negative values while the current remains positive.

Example Low ESR, Low Ripple, Chip Embedded DC-DC Converters

FIG. 16 shows an example chip embedded DC-DC converter with an external ripple voltage feedback circuit 1600. The embodiment of FIG. 16 can include a PCB 1601, driver 1603, first power switch 1605 (such as an eGaN switch), a second power switch 1607 (such as an eGaN switch), an inductor 1609, output capacitor 1621, and output node 1617. FIG. 16 also includes a resistor 1643, capacitor 1645, AC bypass capacitor 1647, a feedback path 1627, a comparator 1629, AND gate 1631, one-shot circuit 1633, inverter 1635, minimum time delay counter 1637, resistor 1639, and resistor 1641.

The output capacitor 1621 can be one or more low ESR capacitors. The low ESR effect can also be achieved by coupling a plurality of capacitors in parallel such that the effective parallel ESR is reduced. For example, each capacitor may have an ESR in the mΩ range (e.g., 1 mΩ, 10 mΩ, 100 mΩ) or lower in the μΩ range (e.g. 10μΩ, 100μΩ), and the arrangement of the capacitors in parallel may reduce the effective parallel ESR even further. As a result of the low ESR, the ripple voltage at node 1617 might be too small to reliably use for feedback, but a low ripple DC output is provided at node 1617. For example, a 1.5 A ripple through the inductor may cause only a 1.5 mV ripple when a 1 mΩ ESR capacitor is used. The one or more output capacitors 1621 can have a total ESR of 1000 mΩ, 100 mΩ, 10 mΩ, 1 mΩ, 100μΩ, any values therebetween, any ranges bounded by any of these values, or a smaller ESR, although in some instances values outside these ranges can be used. In some embodiments, the output voltage of the DC-DC converter can have an AC voltage ripple of 3% or less, 2%, or less, 1% or less, 0.5% or less, 0.1% or less, 0.05% or less, 10 mV or less, 5 mV or less, 3 mV or less, 1 mV or less, 0.5 mV or less, a smaller amount of ripple, a ripple that cannot be reliable detected, an undetectably low amount of ripple, or any ranges bounded by any of these values, although in some instances values outside these ranges can be used. The low ESR and low ripple values discussed herein can relate to other embodiments, as well, such as to the embodiment of FIG. 17.

In order to sense the ripple and provide a feedback voltage, the resistor 1643 can be coupled in series with the capacitor 1645, and the series combination of the resistor 1643 and the capacitor 1645 can be coupled in parallel across the inductor 1609. The capacitor 1645 blocks DC signals. AC signals, such as ripples, can still be sensed. The capacitor 1645 and the resistor 1643 form a voltage divider for AC signals, and the sensed ripple can pass through AC bypass capacitor 1647 to the feedback path 1627. The values of the resistor 1643 and capacitor 1645 can be set such that equation 5 is satisfied:

$\begin{matrix} {\frac{L}{{DCR}_{L}} = {R\; x*C\; x}} & {{Eq}.\mspace{14mu} 5} \end{matrix}$ where L is the value of the inductance of inductor 1609, DCR_(L) is the direct current resistance (“DCR”) of the inductor 1609, Rx is the resistance of the resistor 1643, and Cx is the capacitance of the capacitor 1645. Accordingly, a circuit can be provided to measurably and reliably sense the inductor current ripple independently of the ESR value.

Resistors 1639 and 1641 can form a voltage divider coupled to the output node 1617. The voltage divider can divide the voltage output at the output node 1617. In some implementations, the ripple at the output node 1617 can be small, difficult to detect, within a noise threshold, or otherwise unreliable for modulation purposes due to the low ESR of output capacitor 1621. Accordingly, the voltage divider can primarily act as a DC voltage divider.

The feedback path 1627 is coupled to the voltage divider to receive a DC voltage and is also coupled to the AC bypass capacitor 1647 to sense the ripple voltage. The feedback path is also coupled to a comparator 1629 and compared to a reference voltage. The reference voltage can be provided by a reference voltage generator (not shown), such as a bandgap generator, crystal, digital to analog converter (“DAC”), battery, etc. In some embodiments, a DAC is used to provide the reference voltage, and a digital signal can be provided to the DAC to set a desired reference voltage.

The comparator 1629 can generate a comparator output signal based on a comparison of the feedback signal and the reference voltage. For an example constant on time modulator, the comparator 1629 may generate a high output signal when the feedback signal falls below the reference voltage.

The output of the comparator 1629 can be provided to a one-shot circuit 1633 that generates a constant on time PWM signal, which can be provided to the driver 1603. The output of the one-shot circuit 1633 can also be provided to an inverter 1635, a minimum off time delay circuit 1637, and an AND gate 1631 to prevent the PWM signal from remaining high.

The configuration of the resistor 1643, capacitor 1645, and AC bypass capacitor 1647 can cause a significant, measurable ripple to be detected and injected to the feedback path 1627 despite the low ESR capacitor 1621 and despite the low output ripple. Accordingly, the detected ripple can be larger than the output ripple. The AC ripple injected to the feedback path 1627 can be expressed by:

$\begin{matrix} {V_{c\; x} = \frac{I_{L}*L}{\left( {R_{x}*C_{x}} \right)}} & {{Eq}.\mspace{14mu} 6} \end{matrix}$ where V_(cx) is the ripple voltage on capacitor 1645, I_(L) is the inductor peak to peak current ripple, R_(x) is the resistance of resistor 1643, and C_(x) is the capacitance of capacitor 1645.

In some embodiments, the PCB 1601 and its internal components can be packaged, and users can provide and/or configure the circuit including the inductor 1609, resistor 1643, capacitor 1645, capacitor 1621, capacitor 1645, AC bypass capacitor 1647, resistor 1639, and resistor 1641. In such embodiments, the values of the inductor 1609, resistor 1643, and/or capacitor may be selected and tuned according to equation 6. For example, if the inductor 1609 is changed for an application (e.g., to have a different inductance and/or DCR), a user can solve Eq. 6 and then select, source, and change the resistor 1643 and/or capacitor 1645 to correspond to the new L and DCR_(L) values of the inductor 1609.

In some embodiments, some or all components shown in FIG. 16 can be included in a single package. In some embodiments, including some but not all of the resistor 1643, capacitor 1645, and inductor 1609 in a package can limit the ability to tune the circuit according to equation 6. For example, if the resistor 1643 and capacitor 1645 are included in the package but the inductor 1609 is selected by an end user, then the end user can be restricted to using particular inductors with particular L and DCR_(L) values in order to satisfy equation 6. In such a system and in any improperly tuned system, an improperly selected inductor 1609 can cause system instability and/or malfunction, which may damage components receiving power from the DC-DC converter. In some instances, it can be desirable for the DC-DC converter to be properly tuned and provided as a single packaged device that does not require end user modification. Some embodiments disclosed herein can include the inductor 1609, the resistor 1643, and the capacitor 1645 as an single package.

Example Low ESR, Low Ripple, DC-DC Converters

FIG. 17 shows an example DC-DC converter 1700 (which can be a chip-embedded DC-DC converter, in some embodiments) with an internal ripple voltage feedback circuit. The chip embedded DC-DC converter 1700 includes a package 1701, a driver 1703, a first power switch 1705, a second power switch 1707, and an inductor 1709, which can be similar to other embodiments described herein. The DC-DC converter 1700 can receive an input voltage at a voltage input node 1715 and can provide an output voltage at an output voltage node 1717. An output capacitor 1721 (e.g., a low ESR output capacitor or a plurality of parallel capacitors with a low parallel ESR) can be coupled to the output node 1717. A feedback path 1727 can be coupled from the output node to a comparator 1729. The comparator output can be coupled to an AND gate 1731 and a one-shot circuit 1733 to provide a PWM signal to the driver 1703. A ramp generator 1751 can emulate an inductor ripple current (e.g., emulates the current 1501 in FIG. 15) and outputs a voltage representation of the ripple current (e.g., 1551 in FIG. 15). In some embodiments, the output of the ramp generator 1751 can be combined (e.g., added or subtracted) with a reference voltage at a signal combiner 1753. In some embodiments, the inductor ripple signal output by the ramp generator can be added to the feedback signal instead of being subtracted from the reference voltage. The comparator 1729 can perform a comparison involving the ripple signal output by the ramp generator 1751 and a reference voltage. The result of the comparison can be used in the feedback loop for driving the system (e.g., the switches 1705 and/or 1707).

The inductor 1709 can be included in the chip embedded DC-DC converter package, such as shown in FIG. 1, FIG. 3, FIG. 4A, and FIG. 4B. A low ESR output capacitor 1721 can be coupled to the output node 1717. The at least one output capacitor 1721 can have a low ESR (e.g., similar to the values and ranges discussed herein with regards to the embodiment of FIG. 16). For example, the ESR can be in the mΩ range (e.g., 1 mΩ, 10 mΩ, 100 mΩ) or lower in the μΩ range (e.g. 10 μΩ, 100 μΩ), and the arrangement of the capacitors in parallel may reduce the effective parallel ESR even further. The output voltage can have a low or no AC ripple (e.g., similar to the values and ranges discussed herein with regards to FIG. 16) such that the DC-DC converter can meet low ripple output specifications as required by some devices. However, the same low AC ripple may be small, difficult to detect, within a noise threshold, nonexistent, or otherwise unreliable for modulation purposes (e.g., due to the low ESR of output capacitor 1721), and it can be difficult to use that AC ripple for modulation purposes. The DC output voltage is provided via feedback path 1727 on the feedback path 1727 (e.g., along with any small (but not reliably measurable) AC ripple or no AC ripple at all).

A ramp generator 1751 emulates the inductor ripple independently of the capacitor 1721 and/or its ESR. An example ramp generator is described below with respect to FIG. 18. Inputs to the ramp generator can include the input voltage, the output voltage, a switch signal, and the inductor value. The output of the ramp generator 1751 can be combined with a reference voltage for comparison to the voltage on the feedback path 1727, or the output of the ramp generator 1751 can be combined with the voltage on the feedback path 1727 for comparison to a reference voltage. The voltage reference can be provided, for example, by a DAC. The DAC can generate a voltage output based on a digital input. Accordingly, the DAC voltage can be adjusted in small increments. For example, a 9 bit DAC may have adjustable output voltages in increments of 5 mV. The DAC can be used to set and/or tune an output voltage for the DC-DC converter. Other examples of voltage references include crystals, bandgap references, batteries, etc., any of which may be unable. The reference voltage combined with the emulated inductor ripple can be provided to an input of the comparator 1729, as shown in FIG. 17.

The ramp generator 1751 can be included in the package. The ramp generator 1751 can be included in a chip embedded IC, along with the driver 1703 and other components. The inductor can also be included within the package. The ramp generator 1751 can be tuned and configured for the particular inductor 1709 that is selected within the package before the package is provided to a user. In contrast to designs allowing user selectable inductors with different properties, a designer who selects the packaged inductor 1709 can know the inductor value and characteristics, allowing the designer to extract and/or determine the slew rate of the inductor 1709 and replicate the slew rate using the ramp generator 1751. In some embodiments, instead of using the actual ripple signal (e.g., at the inductor) in the feedback loop, the system can use the ramp generator to emulate the ripple signal (e.g., that is present at the inductor). The ramp generator 1751 can determine an emulated ripple signal based on the values of the input voltage V_(in), V_(out), the inductance values of the inductor L (which can be a known value when the inductor is integrated into the DC-DC converter package), and a switching signal SW. The switching signal can be indicative of the state of one or both of the switches 1705, 1707 and/or the time that one of both of the switches 1705, 1707 changed states (e.g., the HS and LS signals). Since the ramp generator knows the inductance, the input and output voltages, and the timing of the switches, it is able to determine a simulated ripple signal that emulates the actual ripple signal in the circuit (e.g., the ripple at the inductor). The emulated ripple can be proportional to the ripple in the inductor. The emulated ripple can change with the same slope (e.g., at the same rate) that the ripple in the inductor changes. The emulated ripple in a system with a low ESR capacitor 1721 can emulate a ripple that would be seen at node 1417 of FIG. 14 when a low ESR capacitor 1421 is not used.

The inductor ripple signal can be generated to accurately reflect the ripple through inductor 1709. By using a ramp generator to generate the inductor ripple signal, a minimum capacitor ESR is unnecessary for sensing/detecting the AC ripple. Accordingly, the output voltage can be a cleaner DC signal with a smaller or no AC ripple.

In some embodiments, a comparator compares the output of the DC-DC converter to the combination of the reference signal with the emulated inductor ripple. For example, in a constant on time modulation scheme, the comparator can output a high signal when the output signal on the feedback path 1727 falls below the value of the reference voltage combined with the emulated inductor ripple. The high signal can be provided through an AND gate to a one-shot circuit, which provides a constant on time PWM pulse to the driver 1703, which drives switch 1705 on and switch 1707 off. An inverter 1735 and minimum off time delay circuit 1737 coupled to the AND gate can prevent the one-shot circuit 1733 from triggering too frequently by ensuring that that switch 1705 periodically turns off and switch 1707 periodically turns on. Various other implementations can be used to drive the switches based on the output of the comparator 1729.

Although the operation of the circuits in FIG. 16 and FIG. 17 are described with respect to a constant on time modulation scheme, it is understood that the teachings and disclosures herein can apply to any voltage mode modulation scheme, such as a constant off time scheme with the appropriate modifications to the circuitry (e.g., minimum off time delay changed to minimum on time delay, some comparisons and/or signals can be inverted, etc.). Furthermore, the teachings and disclosure herein can further be applied to current mode modulation schemes or voltage modulation schemes.

FIG. 18 shows an example circuit level schematic of a ramp generator 1800. The ramp generator 1800 can include a first current source 1801, a second current source 1803, a capacitor 1805, a ramp voltage output node 1807, a first switch 1809, a second switch 1811, a trim controller 1813, and resistors 1815A, 1815B. The trim controller 1813 and/or the current sources 1801, 1803 can be coupled to the I²C and/or PMBUS to receive trim and/or adjustment commands.

The ramp generator can be configured to generate an output according to the following equations:

$\begin{matrix} {V_{{ramp} - {ON}} = {{\frac{k}{C_{ramp}}\left( {V_{i\; n} - V_{out}} \right)*t_{on}} + V_{o}}} & {{{Eq}.\mspace{14mu} 7}A} \end{matrix}$

$\begin{matrix} {V_{{ramp} - {OFF}} = {{\frac{k}{C_{ramp}}\left( {- V_{out}} \right)*t_{off}} + V_{o}}} & {{{Eq}.\mspace{14mu} 8}A} \end{matrix}$ where V_(ramp-ON) and V_(ramp-OFF) are the respective on and off voltages (output as the inductor ripple output of the ramp generator 1751 in FIG. 17), k can be a constant fixed factor, V_(in) is the input voltage (e.g., the voltage provided at node 1715 in FIG. 17), V_(out) is the output voltage (e.g., the voltage provided at node 1717 in FIG. 17), where k is a number measured in Amps per volts, C_(ramp) is a capacitance of the capacitor 1805, t_(on) is an amount of time that the DC-DC converter is providing power to the inductor (e.g., while switch 1809 is closed and switch 1811 is open), t_(off) is an amount of time that the DC-DC converter is not providing power to the inductor (e.g., while switch 1809 is open and switch 1811 is closed), and V_(o) is a starting voltage. The ripple voltage slew rates (also known as “slopes,” measured in volts per second) are indicated by the coefficients that the time periods (t_(on), t_(off)) are multiplied by:

$\begin{matrix} {{\frac{d}{d\; t}V_{{ramp} - {ON}}} = {\frac{k}{C_{ramp}}\left( {V_{i\; n} - V_{out}} \right)}} & {{{Eq}.\mspace{14mu} 7}B} \end{matrix}$

$\begin{matrix} {{\frac{d}{d\; t}V_{{ramp} - {OFF}}} = {\frac{k}{C_{ramp}}\left( {- V_{out}} \right)}} & {{{Eq}.\mspace{14mu} 8}B} \end{matrix}$

Eq. 7 and Eq. 8 alone do not reveal how to set the value for k to emulate a voltage related to the inductor ripple, which should depend on inductance of inductor 1709. If the ramp generator is configured to emulate the slew rate in Eq. 3C, then Eq. 7B and Eq. 3C can be set equal to each other, where C_(ramp) is set equal to C_(x), and a resistor R_(eq) is selected to replace R_(ESR) such that:

$\begin{matrix} {{\frac{k}{C_{ramp}}\left( {V_{i\; n} - V_{out}} \right)} = {\frac{V_{i\; n} - V_{out}}{L}*R_{eq}}} & {{Eq}.\mspace{14mu} 9} \end{matrix}$

$\begin{matrix} {k = {\frac{C_{ramp}}{L}*R_{eq}}} & {{Eq}.\mspace{14mu} 10} \end{matrix}$

Accordingly, the value for k can be determined, and will be a constant number when the capacitance of capacitor 1805, the resistance of resistors 1815A, 1815B, and the inductance of inductor 1709 are fixed. Furthermore, the relationship between k and inductance is revealed to be an inverse relationship. The constant value k can be determined if the inductance of inductor 1709 is known. Accordingly, the inductance of inductor 1709 can be measured, and the ramp generator can be trimmed and/or configured.

The first current source 1801 can be a voltage controlled current source 1801. The output of the voltage controlled current source 1801 can be controlled, at least in part, by the V_(in) voltage and by k. In some embodiments, the output of the voltage controlled current source can be controlled by the V_(in) voltage multiplied by k. Accordingly, as L increases, k decreases, and current source 1801 can be trimmed to decrease the output current, and as L decreases, the current source 1801 can be trimmed to increase the output current. The current source 1801 is coupled to the first switch 1809 and to ground.

The second current source 1803 can be a voltage controlled current source 1803. The output of the voltage controlled current source 1803 can be controlled, at least in part, by the V_(out) voltage and by k. In some embodiments, the output of the voltage controlled current source can be controlled by the V_(out) voltage multiplied by k. Accordingly, as L increases, k decreases, and the current source 1803 can be trimmed to decrease the output current, and as L decreases, the current source 1803 can be trimmed to increase the output current. The current source 1803 is coupled to the second switch 1811 and to ground.

A trim controller 1813 is coupled to the current sources 1801, 1803. The trim controller 1813 is configured to adjust and/or set the output of the current sources 1801, 1803 based, at least in part, on the inductance of inductor 1709 (including respective or effective parallel inductors in various multi-inductor configurations). In some embodiments, the trim controller 1813 can be configured to adjust and/or set the output of the current sources 1801, 1803 based, at least in part, on the inductance of inductor 1709, the capacitance of capacitor 1805, and/or the resistance of resistors 1815A, 1815B. In some embodiments, the value for C_(ramp)*R_(eq) can be set to a constant value, and the inductance of inductor 1709 is provided to the trim controller 1813.

A first switching signal (e.g., the same signal HS provided to switch 1705 in FIG. 17) can be provided to the first switch 1809. A second signal (e.g., the same signal LS provided to switch 1707 in FIG. 17) can be provided to the second switch 1811. The first and second switches 1809, 1811 can be smaller switches than the power switches 1705, 1707 in FIG. 17.

A capacitor 1805 can have one end coupled between the first switch 1809 and the second switch 1811. Another end of the capacitor 1805 can be coupled to ground.

When the first switch 1809 is closed and the second switch 1811 is open, the first current source 1801 is configured to generate a current controlled by the voltage k*V_(in), charging capacitor 1805 such that a voltage at node 1807 is generated according to Eq. 7A and ramps up as described by Eq. 7B.

When the first switch 1809 is open and the second switch 1811 is closed, the second current source 1803 is configured to generate a current controlled by the voltage k*V_(out), sinking current from capacitor 1805 such that the voltage at node 1807 is decreases according to Eq. 8A, creating a negative voltage ramp as described by Eq. 8B.

As the current is drained from the capacitor 1805, the voltage across the capacitor decreases. Accordingly, the ramp generator can emulate an emulated inductor ripple and provide a usable voltage signal that is independent of the output capacitor and/or ESR.

The increasing and decreasing voltage output by the ramp generator at node 1807 can therefore emulate, be the same as, and/or be proportional to a ripple through the inductor 1709, even when a low ESR capacitor 1721 is used such that a voltage ripple cannot be reliably measured directly from the low ESR capacitor. By providing the inductor 1709, capacitor 1805, and resistors 1815A, 1815B, the values can be determined, and the DC-DC converter shown in FIG. 17 and FIG. 18 can be configured accordingly.

Unlike solutions that require users to configure external components, the packaged chip embedded DC-DC converter shown in FIG. 18 can include a self-contained, tuned feedback system. Accordingly, users do not need to engineer feedback systems, calculate proportions between inductances, DCR's, resistances, and capacitances. Furthermore, integrating the feedback and/or modulation components into a package and/or one or more IC within a package can save space in comparison to using external feedback components.

Example Method of Making and Using Low ESR, Low Ripple, Chip Embedded DC-DC Converters

FIG. 19 shows an example method of making and using a low ESR, low ripple, chip embedded DC-DC converter. The DC-DC can be configured to receive power at an input node at a first input voltage and output power at an output node at second output voltage that is different from the first input voltage.

At block 1901, an IC chip can be embedded in a PCB, as discussed herein. The IC chip can include some or all of: a driver, switches, ramp generator, and modulator circuitry, for example, as shown in FIG. 1, FIG. 3, FIG. 14, FIG. 16, and FIG. 17. In some embodiments, a plurality of IC chips can be embedded in the PCB, for example, as shown in FIG. 11B through FIG. 11D.

At block 1903, one or more inductors can be coupled to the IC chip and to a feedback path, for example, as shown in FIG. 1, FIG. 3, FIG. 14, FIG. 16, and FIG. 17. The inductor(s) and feedback path can be coupled to the output node. In some embodiments, a plurality of inductors can be coupled in a multi-inductor arrangement, for example, as described with respect to FIG. 10 through FIG. 13. The inductors can be configured to receive power and be part of an LC circuit arrangement that stores energy. The LC arrangement can include one or more capacitors, which can be low ESR capacitors. A parallel arrangement of capacitors can provide an effective low ESR. The second output voltage can form across the capacitor(s). Block 1903 can include measuring the inductance of the inductor(s).

At block 1905, a ramp generator can be included. The ramp generator can be included as part of the integrated circuit, as part of a different integrated circuit, included in the PCB, or otherwise included in the DC-DC converter package. An example ramp generator is described with respect to FIG. 17 and FIG. 18. The ramp generator can include a first current source, a second current source, and a capacitor coupled between the first and second current sources.

At block 1907, the ramp generator can be configured to emulate a ripple through the inductor. This can include trimming the first or second current sources based at least in part on a value of the inductor. The value of the inductor can be measured in order to determine the value for trimming. The ripple can be generated independently of the output capacitor and/or the ESR of the output capacitor. The first input voltage, second output voltage, inductance of the inductor, and a switching signal can be provided to the ramp generator. The current sources can switch on and off based on the switching signal. The switching signal can be provided to and/or generated from one or more power switches in the DC-DC converter.

At block 1909, a feedback signal, reference signal, and ripple voltage can be provided for signal modulation. The feedback signal can be a DC output signal (e.g., with no or little AC ripple). The AC ripple on the DC output signal can be insufficient to reliably use for modulation, in some instances. The reference signal can be a desired DC output signal that can be generated by a crystal, bandgap reference, DAC, battery, etc. The ripple voltage can be output by the ramp generator. The feedback signal, reference signal, and ripple voltage can be provided to a comparator.

At block 1911, one or more switches can be modulated and driven based at least in part on the feedback signal, the reference signal, and the ripple voltage. The modulation scheme can be, for example, a voltage mode modulation scheme such as a constant on time or constant off time scheme. The feedback signal can be compared to the reference signal. The ripple voltage can also be included in the comparison. The modulator can generate a control signal, such as a pulse, to drive one or more switches, based at least in part on the comparison.

At block 1913, a modulated output signal can be provided by the DC-DC converter.

Additional Details

The principles and advantages described herein can be implemented in various apparatuses. Also, chip embedded DC-DC converters can be used in various apparatuses for improved performance, and chip embedded DC-DC converters that perform at specifications and provided at lower costs can decrease the overall price of those various apparatuses. Examples of such apparatuses can include, but are not limited to, consumer electronic products, parts of the consumer electronic products, electronic test equipment, etc. Examples of parts of consumer electronic products can include clocking circuits, analog-to-digital converters, amplifiers, rectifiers, programmable filters, attenuators, variable frequency circuits, etc. Examples of the electronic devices can also include memory chips, memory modules, circuits of optical networks or other communication networks, cellular communications infrastructure such as base stations, radar systems, and disk driver circuits. Consumer electronic products can include, but are not limited to, wireless devices, a mobile phone (for example, a smart phone), a wearable computing device such as a smart watch or an ear piece, healthcare monitoring devices, vehicular electronics systems, a telephone, a television, a computer monitor, a computer, a hand-held computer, a tablet computer, a laptop computer, a personal digital assistant (PDA), a microwave, a refrigerator, a stereo system, a cassette recorder or player, a DVD player, a CD player, a digital video recorder (DVR), a VCR, an MP3 player, a radio, a camcorder, a camera, a digital camera, a portable memory chip, a washer, a dryer, a washer/dryer, a copier, a facsimile machine, a scanner, a multi-functional peripheral device, a wrist watch, a clock, etc. Further, apparatuses can include unfinished products.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” “include,” “including,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The words “coupled” or connected”, as generally used herein, refer to two or more elements that can be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number can also include the plural or singular number, respectively. The words “or” in reference to a list of two or more items, is intended to cover all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. The words “and/or” is also intended to cover all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. The term “based on,” as generally used herein, encompasses the following interpretations of the term: solely based on or based at least partly on. All numerical values provided herein are intended to include similar values within a measurement error.

Moreover, conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” “for example,” “such as” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states.

The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure. In addition, certain method or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate. For example, described blocks or states may be performed in an order other than that specifically disclosed, or multiple blocks or states may be combined in a single block or state. The example blocks or states may be performed in serial, in parallel, or in some other manner. Blocks or states may be added to or removed from the disclosed example embodiments. The example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from, or rearranged compared to the disclosed example embodiments.

The teachings of the embodiments provided herein can be applied to other systems, not necessarily the systems described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein can be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein can be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.

Other Embodiments

The following list has example embodiments that are within the scope of this disclosure. The example embodiments that are listed should in no way be interpreted as limiting the scope of the disclosure. Various features of the example embodiments that are listed can be removed, added, or combined to form additional embodiments, which are part of this disclosure:

1. A direct current to direct current (DC-DC) power converter, comprising:

-   -   a lower printed circuit board (PCB) part having a bottom side         and a top side;     -   an upper printed circuit board (PCB) part having a bottom side         and a top side;     -   embedded circuitry that is between the top side of the lower PCB         part and the bottom side of the upper PCB part, the embedded         circuitry comprising:         -   a pulse width modulator; and         -   at least one switch;     -   one or more vias extending through the upper PCB part;     -   an inductor positioned over the top side of the upper PCB part,         wherein the one or more vias are electrically coupled to the         inductor and to the embedded circuitry.

2. The DC-DC power converter of embodiment 1, wherein the embedded circuitry includes an integrated circuit (IC).

3. The DC-DC power converter of embodiment 2, wherein a footprint of the inductor at least partially overlaps a footprint of the integrated circuit.

4. The DC-DC power converter of any one of embodiments 1 to 3, wherein no wire-bonds electrically interconnect the inductor and the embedded circuitry.

5. The DC-DC power converter of any one of embodiments 1 to 4, wherein the circuitry has a switching rate of at least 1 MHz.

6. The DC-DC power converter of any one of embodiments 1 to 4, wherein the circuitry has a switching rate of at least 3 MHz.

7. The DC-DC power converter of any one of embodiments 1 to 4, wherein the circuitry has a switching rate of at least 5 MHz.

8. The DC-DC power converter of any one of embodiments 1 to 7, wherein the circuitry has a switching rate of up to 7 MHz.

9. The DC-DC power converter of any one of embodiments 1 to 8, wherein the at least one switch comprises an enhanced gallium nitride field effect transistor (eGaN FET).

10. The DC-DC power converter of any one of embodiments 1 to 9, further comprising one or more capacitors disposed over the top side of the upper PCB part.

11. The DC-DC power converter of any one of embodiments 1 to 10, further comprising a core disposed between the top side of the lower PCB part and the bottom side of the upper PCB part, wherein the core has one or more pockets formed therein, and wherein the embedded circuitry is disposed in the one or more pockets.

12. The DC-DC power converter of any one of embodiments 1 to 11, wherein the DC-DC power converter has a footprint that is smaller than 25 mm².

13. The DC-DC power converter of any one of embodiments 1 to 11, wherein the DC-DC power converter has a footprint that is smaller than 10 mm².

14. The DC-DC power converter of any one of embodiments 1 to 11, wherein the DC-DC power converter has a footprint that is smaller than 5 mm².

15. The DC-DC power converter of any one of any one of embodiments 1 to 14, wherein the DC-DC power converter has a footprint that is as small as 2 mm².

16. The DC-DC power converter of any one of embodiments 1 to 15, wherein the DC-DC power converter has a footprint area that is between 0.5 and 10 mm² per amperage of current.

17. A direct current to direct current (DC-DC) power converter package comprising:

-   -   an integrated circuit (IC) chip embedded in at least one printed         circuit board (PCB), the IC chip comprising a driver;     -   an inductor positioned outside of the chip embedded package and         coupled to a surface of the chip embedded package; and     -   a via electrically coupling the inductor to the IC chip;     -   wherein a footprint of the inductor overlaps, at least         partially, with a footprint of the IC chip.

18. The DC-DC power converter of embodiment 17, wherein a transistor is embedded in the at least one PCB, and wherein the inductor is electrically coupled to the transistor.

19. The DC-DC power converter of any one of embodiments 17 to 18, wherein the IC chip comprises:

-   -   a pulse width modulator (PWM) controller coupled to the driver;         and     -   a switching transistor coupled to an output of the driver.

20. The DC-DC power converter of any one of embodiments 17 to 19, further comprising a switch comprising enhanced gallium nitride (eGaN).

21. The DC-DC power converter of any one of embodiments 17 to 20, wherein the switch is configured to switch at 4 MHz or faster.

22. The DC-DC power converter of any one of embodiments 17 to 20, wherein the switch is configured to switch at 5 MHz or faster.

23. The DC-DC power converter of any one of embodiments 17 to 19, further comprising a switch comprising at least one of silicon or gallium arsenide.

24. A direct current to direct current (DC-DC) power converter in a single package comprising:

-   -   an enhanced gallium nitride (eGaN) component embedded, at least         partially, inside of a mounting substrate;     -   an inductor mounted outside of the mounting substrate; and     -   a via coupling the inductor to the eGaN component;     -   wherein a footprint of the inductor overlaps, at least         partially, with a footprint of the eGaN component.

25. The DC-DC power converter of embodiment 24, wherein the mounting substrate is a multi-layer PCB.

26. The DC-DC power converter of any one of embodiments 24 to 25, wherein the eGaN component is a switch comprising eGaN, the DC-DC power converter further comprising a driver circuit configured to drive the switch.

27. The DC-DC power converter of any one of embodiments 24 to 26, wherein the driver and the switch are part of an IC chip.

28. The DC-DC power converter of any one of embodiments 24 to 27, wherein the IC chip further comprises a pulse width modulator (PWM) controller.

29. A direct current to direct current (DC-DC) power converter utilizing a chip embedded package, the DC-DC converter comprising:

-   -   an enhanced gallium nitride (eGaN) switch inside of a printed         circuit board (PCB);     -   a pulse width modulator (PWM) controller;     -   a driver embedded inside of the PCB, wherein the PWM controller         and the driver are configured to drive the eGaN switch at a         frequency of 1 MHz or higher;     -   an inductor positioned outside of the chip embedded package and         coupled to a surface of the PCB; and     -   a via electrically coupling the inductor to the eGaN switch.

30. The DC-DC power converter of embodiment 29, wherein the driver is configured to drive the eGaN switch at a frequency of 5 MHz or higher.

31. A direct current to direct current (DC-DC) power converter comprising:

-   -   a printed circuit board; and     -   an integrated circuit inside of the printed circuit board, the         integrated circuit comprising a driver.

32. The DC-DC power converter of embodiment 31, further comprising an inductor electrically coupled to the integrated circuit by one or more vias that extend through the printed circuit board.

33. The DC-DC power converter of embodiment 32, wherein the inductor has a footprint that at least partially overlaps a footprint of the integrated circuit.

34. A direct current to direct current (DC-DC) power converter comprising:

-   -   an integrated circuit comprising a driver; and     -   an inductor vertically stacked above the integrated circuit such         that a footprint of the inductor overlaps, at least partially,         with a footprint of the integrated circuit, wherein the inductor         is electrically coupled to the integrated circuit.

35. The DC-DC converter of embodiment 34, further comprising a printed circuit board (PCB) having a first side and a second side that is opposite the first side, wherein the integrated circuit is mounted on the first side of the PCB, and wherein the inductor is mounted on the second side of the PCB.

36. The DC-DC converter of embodiment 35, wherein the inductor is electrically coupled to the integrated circuit by one or more vias that extend through the printed circuit board.

37. A direct current to direct current (DC-DC) buck converter comprising:

-   -   one or more switches;     -   a driver configured to drive the one or more switches; and     -   an inductor electrically coupled to the switches;     -   wherein the footprint of the DC-DC buck converter is less than         65 mm²;     -   wherein the DC-DC buck converter is configured to receive at         least 20 amps of current; and     -   wherein the DC-DC buck converter is configured to output at         least 20 amps of current.

38. A direct current to direct current (DC-DC) power converter comprising:

-   -   one or more switches;     -   a driver configured to drive the one or more switches at a         frequency, the frequency being between 1 and 5 MHz inclusive;         and     -   an inductor electrically coupled to the one or more switches;     -   wherein the footprint of the DC-DC converter is less than or         equal to 10 mm²;     -   wherein the DC-DC converter is configured to receive at least 5         amps of current;     -   wherein the DC-DC converter is configured to output at least 5         amps of current.

39. A direct current to direct current (DC-DC) power converter comprising:

-   -   a first switch coupled to a first inductor;     -   a second switch coupled to a second inductor; and     -   an integrated circuit chip embedded in a printed circuit board;     -   wherein the first switch and the second switch are coupled to a         modulator; and     -   wherein the first inductor and the second inductor are coupled         to a voltage output node.

40. The direct current to direct current (DC-DC) power converter of embodiment 39, wherein the modulator is included in the integrated circuit chip.

41. The direct current to direct current (DC-DC) power converter of any one of embodiments 39 to 40, wherein the modulator is configured to cause the first switch and the second switch to operate output of phase with a synchronous period.

42. The direct current to direct current (DC-DC) power converter of any one of embodiments 39 to 41, wherein an output signal at the output node is a superposition of a first signal through the first inductor and a second signal through the second inductor.

43. A direct current to direct current (DC-DC) power converter comprising:

-   -   an integrated circuit chip embedded in a printed circuit board,         the integrated circuit chip comprising a driver;     -   a first switch coupled to the driver;     -   an inductor coupled to the first switch; and     -   a feedback path from an output node to a modulator circuit.

44. The direct current to direct current (DC-DC) power converter of embodiment 43, wherein the modulator circuit is a voltage mode modulator circuit.

45. The direct current to direct current (DC-DC) power converter of any one of embodiments 43 to 44, wherein the modulator circuit is a constant on time or constant off time modulator circuit.

46. The direct current to direct current (DC-DC) power converter of any one of embodiments 43 to 45, wherein the modulator circuit is included in the integrated circuit chip.

47. The direct current to direct current (DC-DC) power converter of any one of embodiments 43 to 46, wherein the modulator circuit and the inductor are included in a package with the integrated circuit chip.

48. A direct current to direct current (DC-DC) power converter comprising:

-   -   an integrated circuit chip embedded in a printed circuit board,         the integrated circuit chip comprising a driver;     -   a first switch coupled to the driver;     -   an inductor coupled to the first switch;     -   a feedback path from an output node to a modulator circuit; and     -   a ramp generator.

49. The direct current to direct current (DC-DC) power converter of embodiment 48, wherein the feedback path and an output from the ramp generator are coupled to a comparator.

50. The direct current to direct current (DC-DC) power converter of embodiment 49, further comprising a reference voltage source coupled to the comparator.

51. The direct current to direct current (DC-DC) power converter of any one of embodiments 48 to 50, wherein the ramp generator is configured to emulate a ripple current through the inductor.

52. The direct current to direct current (DC-DC) power converter of any one of embodiments 48 to 51, wherein the ramp generator comprises:

-   -   a first current source;     -   a second current source; and     -   a capacitor.

53. The direct current to direct current (DC-DC) power converter of embodiment 52, wherein the first current source and the second current source are configured to be trimmed based, at least in part, on an inductance of the inductor.

54. The direct current to direct current (DC-DC) power converter of any one of embodiments 48 to 53, wherein the ramp generator and the inductor are included in the same DC-DC power converter package.

55. The direct current to direct current (DC-DC) power converter of any one of embodiments 48 to 54, wherein the ramp generator is configured to generate an output signal that is unaffected by an output capacitor coupled to the inductor.

56. The direct current to direct current (DC-DC) power converter of any one of embodiments 48 to 55, wherein the ramp generator is configured to generate an output signal that is independent from the equivalent series resistance (ESR) of an output capacitor coupled to the inductor.

57. The direct current to direct current (DC-DC) power converter of any one of embodiments 48 to 56, further comprising an output capacitor having a sufficiently low ESR such that a ripple voltage across the output capacitor is too small to reliably provide to a modulation circuit.

58. A ramp generator comprising:

-   -   a first current source coupled to a supply voltage;     -   a second current source coupled to ground; and     -   a capacitor coupled between the first current source and the         second current source.

59. The ramp generator of embodiment 58, wherein the ramp generator is configured to emulate a ripple current through an inductor in a DC-DC converter.

60. The ramp generator of any one of embodiments 58 to 59, wherein the output of the first current source is based, at least in part, on an input voltage to a DC-DC converter.

61. The ramp generator of any one of embodiments 58 to 60, wherein the output of the first current source is based, at least in part, on an inductance of an inductor in a DC-DC converter.

62. The ramp generator of any one of embodiments 58 to 61, wherein the output of the second current source is based, at least in part, on an inductance of an inductor in a DC-DC converter.

63. The ramp generator of any one of embodiments 58 to 62, wherein the output of the second current source is based, at least in part, on an inductance of an inductor in a DC-DC converter.

64. The ramp generator of any one of embodiments 58 to 63, wherein the first current source is configured to be trimmed based, at least in part, on an inductance of an inductor in a DC-DC converter.

65. The ramp generator of any one of embodiments 58 to 64, wherein the second current source is configured to be trimmed based, at least in part, on an inductance of an inductor in a DC-DC converter.

66. A method for making a chip embedded direct current to direct current converter comprising:

-   -   embedding an integrated circuit chip in a printed circuit board;     -   coupling a first inductor to the printed circuit board; and     -   coupling a second inductor to the printed circuit board, the         first inductor and the second inductor both coupled to an output         node.

67. A method for converting first direct current voltage to a second direct current voltage comprising:

-   -   driving a first switch coupled to a first inductor;     -   driving a second switch coupled to a second inductor, wherein         the first switch and the second switch are coupled to an output         node; and     -   modulating the driving of the first switch and the second switch         out of phase;     -   wherein at least one of a driver or a modulator is included in a         chip embedded in a printed circuit board.

68. A method for making a chip embedded direct current to direct current converter comprising:

-   -   embedding an integrated circuit chip in a printed circuit board;     -   coupling an inductor between the integrated circuit chip and an         output node; and     -   providing a feedback path from the output node to a modulator         circuit, wherein the modulator circuit includes a ramp         generator.

69. The method of embodiment 68, wherein the modulator circuit is included in the printed circuit board.

70. The method of any one of embodiments 68 to 69, wherein the modulator circuit is a constant on time or constant off time modulator circuit.

71. The method of any one of embodiments 68 to 70, wherein the ramp generator is included in the integrated circuit.

72. The method of any one of embodiments 68 to 71, further comprising:

-   -   trimming the ramp generator based at least in part on the         property of the inductor.

73. The method of any one of embodiments 68 to 72, wherein the ramp generator is the ramp generator of any one of embodiments 58 to 65.

74. A method for using a direct current to direct current converter comprising:

-   -   receiving input power at an input node;     -   providing power through a switch to an inductor;     -   storing energy in an output capacitor such that an output         voltage forms across the output capacitor;     -   providing output power at the output voltage to an output node;     -   providing the output voltage to a modulator circuit;     -   generating a ripple voltage that is independent of an output         capacitor;     -   providing the ripple voltage to the modulator circuit;     -   modulating the switch based at least in part on an output of the         modulator circuit.

75. The method of embodiment 74, further comprising comparing at least two of: the ripple voltage, a reference voltage, and the output voltage.

76. The method of any one of embodiments 74 to 75, further comprising trimming a current source based at least in part on an inductance of the inductor.

77. The method of any one of embodiments 74 to 76, wherein the ripple voltage is generated by a ramp generator configured to emulate a current through the inductor.

78. A direct current to direct current (DC-DC) power converter package comprising:

-   -   an integrated circuit (IC) chip embedded in at least one printed         circuit board (PCB), the IC chip comprising a driver;     -   an inductor positioned outside of the chip embedded package and         coupled to a surface of the chip embedded package; and     -   an overcurrent protection circuit configured to detect when a         current provided to the inductor exceeds a limit.

79. The direct current to direct current (DC-DC) power converter package of embodiment 78, wherein:

-   -   the overcurrent protection circuit comprises a current source         configured to be adjusted or trimmed based at least in part on         an Inter-Integrated Circuit or Power Management Bus command;     -   a saturation inductance of the inductor exceeds the limit and         exceeds the limit by less than 50%;     -   the limit exceeds a maximum specified DC current specification         plus maximum alternating current ripple specification by less         than 50%.

80. A direct current to direct current (DC-DC) power converter package comprising:

-   -   an integrated circuit (IC) chip embedded in at least one printed         circuit board (PCB), the IC chip comprising a driver;     -   an inductor positioned outside of the chip embedded package and         coupled to a surface of the chip embedded package; and     -   an Inter-Integrated Circuit or Power Management Bus.

81. A direct current to direct current (DC-DC) power converter package of embodiment 80, wherein:

-   -   the Inter-Integrated Circuit or Power Management Bus is coupled         to at least one current source and configured to provide a         protocol command to adjust or trim the current source.

82. A direct current to direct current (DC-DC) power converter package of any one of embodiments 80 to 81, wherein:

-   -   the Inter-Integrated Circuit or Power Management Bus is coupled         to at least one current source and configured to provide a         protocol command to set or adjust a reference value provided to         a comparator.

83. A direct current to direct current (DC-DC) power converter package of any one of embodiments 80 to 82, wherein the Inter-Integrated Circuit or Power Management Bus is configured to communicate protocols comprising instructions to perform at least one of:

-   -   turn on or off the DC-DC power converter package, change a low         power or sleep mode of the DC-DC power converter package, read         out information about current settings of the DC-DC power         converter package, read out diagnostic and/or technical         information about the DC-DC power converter package, set or         change an output voltage provided by the DC-DC power converter         package.

84. A direct current to direct current (DC-DC) power converter package of any one of embodiments 80 to 83, wherein a Power Management Protocol is implemented as an interconnect layer on top of an Inter-Integrated Circuit implementation. 

What is claimed is:
 1. A direct current to direct current (DC-DC) power converter, comprising: a lower printed circuit board (PCB) part having a bottom side and a top side; an upper printed circuit board (PCB) part having a bottom side and a top side; an embedded integrated circuit that is embedded between the bottom side of the upper PCB part and the top side of the lower PCB part, wherein the embedded integrated circuit comprises: a pulse width modulator (PWM) controller configured to generate one or more PWM signals; a driver configured to generate one or more driver signals based at least in part on the one or more PWM signals, the driver being coupled within the embedded integrated circuit to the PWM controller; a first power switch configured to receive at least one of the one or more driver signals, the first power switch being coupled within the embedded integrated circuit to the driver; and a second power switch configured to receive at least one of the one or more driver signals, the second power switch being coupled within the embedded integrated circuit to the driver; at least one via extending through the upper PCB part; an inductor positioned over the top side of the upper PCB part, wherein the inductor is electrically coupled by way of the at least one via to the first and second power switches, and wherein a footprint of the inductor overlaps, at least partially, with a footprint of the embedded integrated circuit; an input port coupled to at least one of the first and second power switches, the input port configured to receive an input signal at an input voltage; an output port coupled to the inductor, the output port configured to provide an output signal at an output voltage that is different than the input voltage, wherein the output voltage is based, at least in part, on the first and second power switches causing the inductor to charge and discharge energy; and a feedback system comprising: a feedback path coupled to the output port, the feedback path configured to provide an indication of the output voltage; and a ramp generator that is configured to generate a signal that emulates a current ripple through the inductor; wherein the feedback system is configured to provide a feedback signal based at least in part on the indication of the output voltage from the feedback path and the signal provided by the ramp generator, and wherein the first and second power switches are driven based at least in part on the feedback signal.
 2. The DC-DC power converter of claim 1, wherein the ramp generator is configured to generate the signal that emulates the current ripple through the inductor at least in part using: a first input indicative of the input voltage; a second input indicative of the output voltage; a third input indicative of an inductance value of the inductor; and a fourth input of a switching signal.
 3. The DC-DC power converter of claim 1, wherein the ramp generator comprises: a first current source configured to generate a current based, at least in part, on the input voltage; a second current source configured to generate a current based, at least in part, on the output voltage; a third switch configured to receive at least one of the one or more driver signals, the third switch coupled to the first current source; a fourth switch configured to receive at least one of the one or more driver signals, the fourth switch coupled to the second current source; and a capacitor coupled to the third switch and to the fourth switch.
 4. The DC-DC power converter of claim 1, wherein the first and second power switches are enhanced gallium nitride (eGaN) field effect transistors.
 5. The DC-DC power converter of claim 1, wherein the PWM controller is configured to cause the driver to toggle the switches at frequencies of at least 4 MHz.
 6. The DC-DC power converter of claim 1, wherein the DC-DC power converter is configured to handle a current amount and wherein the DC-DC power converter has a footprint area that is between 1.0 mm² and 10 mm² per amperage of the current amount.
 7. The DC-DC power converter of claim 1, wherein one of the inductor and the integrated circuit has a footprint included entirely within a footprint of the other of the inductor and the integrated circuit.
 8. The DC-DC power converter of claim 1, wherein the input port, the output port, and a ground port are exposed outside of a package surrounding the inductor, and wherein the input port is coupled to the first power switch without wire bonds, the output port is coupled to the inductor without wire bonds, the second power switch is coupled to a ground without wire bonds, and the inductor is coupled to the first and second power switches without wire bonds.
 9. The DC-DC power converter of claim 1, further comprising a second inductor coupled to the PCB, the second inductor also being coupled to the output node, wherein the first inductor and the second inductor are driven out of phase with each other.
 10. The DC-DC power converter of claim 1, wherein the embedded integrated circuit includes the ramp generator.
 11. A direct current to direct current (DC-DC) power converter, comprising: a printed circuit board (PCB); embedded circuitry that is embedded within the PCB, wherein the embedded circuitry comprises: a pulse width modulator (PWM) controller configured to generate one or more PWM signals; and a driver configured to generate one or more driver signals based at least in part on the one or more PWM signals, the driver being coupled to the PWM controller within the embedded circuitry; a first power switch configured to receive at least one of the one or more driver signals, the first power switch being coupled to the driver within the embedded circuitry; and a second power switch configured to receive at least one of the one or more driver signals, the second power switch being coupled to the driver within the embedded circuitry; at least one via extending through a part of the PCB; an inductor positioned outside of the PCB and coupled to an upper part of the PCB, wherein the inductor is electrically coupled by way of the at least one via to the first and second power switches, and wherein a footprint of the inductor overlaps, at least partially, with a footprint of the embedded circuitry; an input port coupled to at least one of the first and second power switches, the input port configured to receive an input signal at an input voltage; and an output port coupled to the inductor, the output port configured to provide an output signal at an output voltage that is different than the input voltage; wherein the DC-DC power converter is configured to handle a current amount and wherein the DC-DC power converter has a footprint area that is between 1.0 mm² and 10 mm² per amperage of the current amount.
 12. The DC-DC power converter of claim 11, further comprising: an output capacitor coupled to the inductor and also coupled to the output port, the output capacitor having a low equivalent series resistance (ESR), wherein a voltage ripple in the output voltage is 2% or less; and a feedback system comprising a ramp generator configured to generate a voltage ripple that emulates a current ripple through the inductor.
 13. The DC-DC power converter of claim 11, wherein the first power switch and the second power switch are enhanced gallium nitride (eGaN) field effect transistors.
 14. The DC-DC power converter of claim 11, wherein the input port is configured to receive at least 20 amps of current, the output port is configured to provide at least 20 amps of current, and the footprint of the DC-DC power converter is less than 65 mm².
 15. The DC-DC power converter of claim 11, wherein the inductor and the embedded circuitry are interconnected without wire bonds.
 16. The DC-DC power converter of claim 11, wherein the embedded circuitry comprises an integrated circuit that includes the PWM controller, the driver, the first power switch, and the second power switch.
 17. A direct current to direct current (DC-DC) power converter, comprising: a printed circuit board (PCB); embedded circuitry that is embedded within the PCB, wherein the embedded circuitry comprises: a pulse width modulator (PWM) controller configured to generate one or more PWM signals; and a driver configured to generate one or more driver signals based at least in part on the one or more PWM signals, the driver being coupled to the PWM controller within the embedded circuitry; a first enhanced gallium nitride field effect transistor (eGaN FET) configured to receive at least one of the one or more driver signals, the first eGaN FET being coupled to the driver within the embedded circuitry; and a second eGaN FET configured to receive at least one of the one or more driver signals, the second eGaN FET being coupled to the driver within the embedded circuitry; at least one via extending through a part of the PCB; and an inductor positioned outside of the PCB and coupled to an upper part of the PCB, wherein the inductor is electrically coupled by way of the at least one via to the first and second eGaN FETs, and wherein a footprint of the inductor overlaps, at least partially, with a footprint of the embedded circuitry.
 18. The DC-DC power converter of claim 17, wherein the PWM controller is configured to cause the driver to toggle the first and second eGaN FETs at frequencies between 4 and 10 MHz.
 19. The DC-DC power converter of claim 17, wherein the DC-DC power converter is configured to handle a current amount and wherein the DC-DC power converter has a footprint area that is between 1.0 mm² and 10 mm² per amperage of the current amount.
 20. The DC-DC power converter of claim 17, wherein the embedded circuitry comprises a ramp generator configured to generate a signal that emulates a current ripple through the inductor. 